cs-cmdutils


Namecs-cmdutils JSON
Version 20241222.1 PyPI version JSON
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SummaryConvenience functions for working with the cmd stdlib module, the BaseCommand class for constructing command line programmes, and other command line related stuff.
upload_time2024-12-21 23:00:46
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licenseGNU General Public License v3 or later (GPLv3+)
keywords python2 python3
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            Convenience functions for working with the cmd stdlib module,
the BaseCommand class for constructing command line programmes,
and other command line related stuff.

*Latest release 20241222.1*:
* BaseCommand.cmd_info: use pformat instead of str.
* BaseCommand.cmd_repl: enumerate the options as top level names in the banner.
* If run as main programme, run a demo command.

## <a name="BaseCommand"></a>Class `BaseCommand`

A base class for handling nestable command lines.

This class provides the basic parse and dispatch mechanisms
for command lines.
To implement a command line
one instantiates a subclass of `BaseCommand`:

    class MyCommand(BaseCommand):
        GETOPT_SPEC = 'ab:c'
        USAGE_FORMAT = r"""and provides either a `main` method if the command has no subcommands
or a suite of `cmd_`*subcommand* methods, one per subcommand.

Running a command is done by:

    MyCommand(argv).run()

Modules which implement a command line mode generally look like this:

    ... imports etc ...
    def main(argv=None, **run_kw):
        """ The command line mode.
        """
        return MyCommand(argv).run(**run_kw)
    ... other code ...
    class MyCommand(BaseCommand):
    ... other code ...
    if __name__ == '__main__':
        sys.exit(main(sys.argv))

Instances have a `self.options` attribute on which optional
modes are set,
avoiding conflict with the attributes of `self`.

Subclasses with no subcommands
generally just implement a `main(argv)` method.

Subclasses with subcommands
should implement a `cmd_`*subcommand*`(argv)` instance method
for each subcommand.
If a subcommand is itself implemented using `BaseCommand`
then it can be a simple attribute:

    cmd_subthing = SubThingCommand

Returning to methods, if there is a paragraph in the method docstring
commencing with `Usage:` then that paragraph is incorporated
into the main usage message automatically.
Example:

    def cmd_ls(self, argv):
        """ Usage: {cmd} [paths...]
              Emit a listing for the named paths.

            Further docstring non-usage information here.
        """
        ... do the "ls" subcommand ...

The subclass is customised by overriding the following methods:
* `apply_opt(opt,val)`:
  apply an individual getopt global command line option
  to `self.options`.
* `apply_opts(opts)`:
  apply the `opts` to `self.options`.
  `opts` is an `(option,value)` sequence
  as returned by `getopot.getopt`.
  The default implementation iterates over these and calls `apply_opt`.
* `run_context()`:
  a context manager to provide setup or teardown actions
  to occur before and after the command implementation respectively,
  such as to open and close a database.
* `cmd_`*subcmd*`(argv)`:
  if the command line options are followed by an argument
  whose value is *subcmd*,
  then the method `cmd_`*subcmd*`(subcmd_argv)`
  will be called where `subcmd_argv` contains the command line arguments
  following *subcmd*.
* `main(argv)`:
  if there are no `cmd_`*subcmd*` methods then method `main(argv)`
  will be called where `argv` contains the command line arguments.

Editorial: why not arparse?
Primarily because when incorrectly invoked
an argparse command line prints the help/usage messgae
and aborts the whole programme with `SystemExit`.
But also, I find the whole argparse `add_argument` thing cumbersome.

Usage summary:

    Usage: base [common-options...] [-a] [-b bvalue] [-c] [--] arguments...
        -a    Do it all.
        -b    But using bvalue.
        -c    The 'c' option!
      """
      ...
      Subcommands:
        help [common-options...] [-l] [-s] [subcommand-names...]
          Print help for subcommands.
          This outputs the full help for the named subcommands,
          or the short help for all subcommands if no names are specified.
          Options:
            -l  Long listing.
            -r  Recurse into subcommands.
            -s  Short listing.
        info [common-options...] [field-names...]
          Recite general information.
          Explicit field names may be provided to override the default listing.
        repl [common-options...]
          Run a REPL (Read Evaluate Print Loop), an interactive Python prompt.
          Options:
            --banner banner  Banner.
        shell [common-options...]
          Run a command prompt via cmd.Cmd using this command's subcommands.

*`BaseCommand.__init__(self, argv=None, *, cmd=None, options=None, **kw_options)`*:
Initialise the command line.
Raises `GetoptError` for unrecognised options.

Parameters:
* `argv`:
  optional command line arguments
  including the main command name if `cmd` is not specified.
  The default is `sys.argv`.
  The contents of `argv` are copied,
  permitting desctructive parsing of `argv`.
* `cmd`:
  optional keyword specifying the command name for context;
  if this is not specified it is taken from `argv.pop(0)`.
* `options`:
  an optional keyword providing object for command state and context.
  If not specified a new `self.Options` instance
  is allocated for use as `options`.
  The default `Options` class is `BaseCommandOptions`,
  a dataclass with some prefilled attributes and properties
  to aid use later.
Other keyword arguments are applied to `self.options`
as attributes.

The `cmd` and `argv` parameters have some fiddly semantics for convenience.
There are 3 basic ways to initialise:
* `BaseCommand()`: `argv` comes from `sys.argv`
  and the value for `cmd` is derived from `argv[0]`
* `BaseCommand(argv)`: `argv` is the complete command line
  including the command name and the value for `cmd` is
  derived from `argv[0]`
* `BaseCommand(argv, cmd=foo)`: `argv` is the command
  arguments _after_ the command name and `cmd` is set to
  `foo`

The command line arguments are parsed according to
the optional `GETOPT_SPEC` class attribute (default `''`).
If `getopt_spec` is not empty
then `apply_opts(opts)` is called
to apply the supplied options to the state
where `opts` is the return from `getopt.getopt(argv,getopt_spec)`.

After the option parse,
if the first command line argument *foo*
has a corresponding method `cmd_`*foo*
then that argument is removed from the start of `argv`
and `self.cmd_`*foo*`(argv,options,cmd=`*foo*`)` is called
and its value returned.
Otherwise `self.main(argv,options)` is called
and its value returned.

If the command implementation requires some setup or teardown
then this may be provided by the `run_context`
context manager method,
called with `cmd=`*subcmd* for subcommands
and with `cmd=None` for `main`.

*`BaseCommand.Options`*

*`BaseCommand.SubCommandClass`*

*`BaseCommand.apply_opt(self, opt, val)`*:
Handle an individual global command line option.

This default implementation raises a `NotImplementedError`.
It only fires if `getopt` actually gathered arguments
and would imply that a `GETOPT_SPEC` was supplied
without an `apply_opt` or `apply_opts` method to implement the options.

*`BaseCommand.apply_opts(self, opts)`*:
Apply command line options.

Subclasses can override this
but it is usually easier to override `apply_opt(opt,val)`.

*`BaseCommand.apply_preargv(self, argv)`*:
Do any preparsing of `argv` before the subcommand/main-args.
Return the remaining arguments.

This default implementation applies the default options
supported by `self.options` (an instance of `self.Options`
class).

*`BaseCommand.cmd_help(self, argv)`*:
Usage: {cmd} [-l] [-s] [subcommand-names...]
Print help for subcommands.
This outputs the full help for the named subcommands,
or the short help for all subcommands if no names are specified.
Options:
  -l  Long listing.
  -r  Recurse into subcommands.
  -s  Short listing.

*`BaseCommand.cmd_info(self, argv, *, field_names=None, skip_names=None)`*:
Usage: {cmd} [field-names...]
  Recite general information.
  Explicit field names may be provided to override the default listing.

This default method recites the values from `self.options`,
excluding the basic fields from `BaseCommandOptions` other
than `cmd` and `dry_run`.

This base method provides two optional parameters to allow
subclasses to tune its behaviour:
- `field_namees`: an explicit list of options attributes to print
- `skip_names`: a list of option attributes to not print
  if `field_names` is not specified; the default is the
  field names of `BaseCommandOptions` excepting `cmd` and
  `dry_run`

*`BaseCommand.cmd_repl(self, argv)`*:
Usage: {cmd}
Run a REPL (Read Evaluate Print Loop), an interactive Python prompt.
Options:
  --banner banner  Banner.

*`BaseCommand.cmd_shell(*a, upd: Optional[cs.upd.Upd] = <function uses_upd.<locals>.<lambda> at 0x10473dda0>, **kw)`*:
Usage: {cmd}
Run a command prompt via cmd.Cmd using this command's subcommands.

*`BaseCommand.cmdloop(self, intro=None)`*:
Use `cmd.Cmd` to run a command loop which calls the `cmd_`* methods.

*`BaseCommand.extract_usage(cmd=None)`*:
Extract the `Usage:` paragraph from `cls__doc__` if present.
Return a 2-tuple of `(doc_without_usage,usage_text)`
being the remaining docstring and a full usage message.

*Note*: this actually sets `cls.USAGE_FORMAT` if that does
not already exist.

*`BaseCommand.getopt_error_handler(cmd, options, e, usage, subcmd=None)`*:
The `getopt_error_handler` method
is used to control the handling of `GetoptError`s raised
during the command line parse
or during the `main` or `cmd_`*subcmd*` calls.

This default handler issues a warning containing the exception text,
prints the usage message to standard error,
and returns `True` to indicate that the error has been handled.

The handler is called with these parameters:
* `cmd`: the command name
* `options`: the `options` object
* `e`: the `GetoptError` exception
* `usage`: the command usage or `None` if this was not provided
* `subcmd`: optional subcommand name;
  if not `None`, is the name of the subcommand which caused the error

It returns a true value if the exception is considered handled,
in which case the main `run` method returns 2.
It returns a false value if the exception is considered unhandled,
in which case the main `run` method reraises the `GetoptError`.

To let the exceptions out unhandled
this can be overridden with a method which just returns `False`.

Otherwise,
the handler may perform any suitable action
and return `True` to contain the exception
or `False` to cause the exception to be reraised.

*`BaseCommand.handle_signal(self, sig, frame, *, runstate: Optional[cs.resources.RunState] = <function uses_runstate.<locals>.<lambda> at 0x10473d760>)`*:
The default signal handler, which cancels the default `RunState`.

*`BaseCommand.has_subcommands()`*:
Test whether the class defines additional subcommands.

*`BaseCommand.method_cmdname(method_name: str)`*:
The `cmd` value from a method name.

*`BaseCommand.poparg(argv: List[str], *specs, unpop_on_error: bool = False, opt_spec_class=None)`*:
Pop the leading argument off `argv` and parse it.
Return the parsed argument.
Raises `getopt.GetoptError` on a missing or invalid argument.

This is expected to be used inside a `main` or `cmd_*`
command handler method or inside `apply_preargv`.

You can just use:

    value = argv.pop(0)

but this method provides conversion and valuation
and a richer failure mode.

Parameters:
* `argv`: the argument list, which is modified in place with `argv.pop(0)`
* the argument list `argv` may be followed by some help text
  and/or an argument parser function.
* `validate`: an optional function to validate the parsed value;
  this should return a true value if valid,
  or return a false value or raise a `ValueError` if invalid
* `unvalidated_message`: an optional message after `validate`
  for values failing the validation
* `unpop_on_error`: optional keyword parameter, default `False`;
  if true then push the argument back onto the front of `argv`
  if it fails to parse; `GetoptError` is still raised

Typical use inside a `main` or `cmd_*` method might look like:

    self.options.word = self.poparg(argv, int, "a count value")
    self.options.word = self.poparg(
        argv, int, "a count value",
       lambda count: count > 0, "count should be positive")

Because it raises `GetoptError` on a bad argument
the normal usage message failure mode follows automatically.

Demonstration:

    >>> argv = ['word', '3', 'nine', '4']
    >>> BaseCommand.poparg(argv, "word to process")
    'word'
    >>> BaseCommand.poparg(argv, int, "count value")
    3
    >>> BaseCommand.poparg(argv, float, "length")
    Traceback (most recent call last):
      ...
    getopt.GetoptError: length 'nine': float('nine'): could not convert string to float: 'nine'
    >>> BaseCommand.poparg(argv, float, "width", lambda width: width > 5)
    Traceback (most recent call last):
      ...
    getopt.GetoptError: width '4': invalid value
    >>> BaseCommand.poparg(argv, float, "length")
    Traceback (most recent call last):
      ...
    getopt.GetoptError: length: missing argument
    >>> argv = ['-5', 'zz']
    >>> BaseCommand.poparg(argv, float, "size", lambda size: size > 0, "size should be >0")
    Traceback (most recent call last):
      ...
    getopt.GetoptError: size '-5': size should be >0
    >>> argv  # -5 was still consumed
    ['zz']
    >>> BaseCommand.poparg(argv, float, "size2", unpop_on_error=True)
    Traceback (most recent call last):
      ...
    getopt.GetoptError: size2 'zz': float('zz'): could not convert string to float: 'zz'
    >>> argv  # zz was pushed back
    ['zz']

*`BaseCommand.popopts(self, argv, options, **opt_specs)`*:
OBSOLETE popopts

A convenience shim which returns `self.options.popopts(argv,**opt_specs)`.

*`BaseCommand.repl(self, *argv, banner=None, local=None)`*:
Run an interactive Python prompt with some predefined local names.
Aka REPL (Read Evaluate Print Loop).

Parameters:
* `argv`: any notional command line arguments
* `banner`: optional banner string
* `local`: optional local names mapping

The default `local` mapping is a `dict` containing:
* `argv`: from `argv`
* `options`: from `self.options`
* `self`: from `self`
* the attributes of `options`
* the attributes of `self`

*`BaseCommand.run(self, **kw_options)`*:
Run a command.
Returns the exit status of the command.
May raise `GetoptError` from subcommands.

Any keyword arguments are used to override `self.options` attributes
for the duration of the run,
for example to presupply a shared `Upd` from an outer context.

If the first command line argument *foo*
has a corresponding method `cmd_`*foo*
then that argument is removed from the start of `argv`
and `self.cmd_`*foo*`(cmd=`*foo*`)` is called
and its value returned.
Otherwise `self.main(argv)` is called
and its value returned.

If the command implementation requires some setup or teardown
then this may be provided by the `run_context()`
context manager method.

*`BaseCommand.run_context(*a, upd: Optional[cs.upd.Upd] = <function uses_upd.<locals>.<lambda> at 0x10473d4e0>, **kw)`*:
The context manager which surrounds `main` or `cmd_`*subcmd*.
Normally this will have a bare `yield`, but you can yield
a not `None` value to exit before the command, for example
if the run setup fails.

This default does several things, and subclasses should
override it like this:

    @contextmanager
    def run_context(self):
      with super().run_context():
        try:
          ... subclass context setup ...
            yield
        finally:
          ... any unconditional cleanup ...

This base implementation does the following things:
- provides a `self.options` which is a copy of the original
  `self.options` so that it may freely be modified during the
  command
- provides a prevailing `RunState` as `self.options.runstate`
  if one is not already present
- provides a `cs.upd.Upd` context for status lines
- catches `self.options.runstate_signals` and handles them
  with `self.handle_signal`

*`BaseCommand.subcommand`*

*`BaseCommand.subcommand_usage_text(self, subcmd, usage_format_mapping=None, short=False)`*:
Return the usage text for a subcommand.

*`BaseCommand.subcommands`*

*`BaseCommand.usage_text(self, **subcommand_kw)`*:
Compute the "Usage:" message for this class.
Parameters are as for `SubCommand.usage_text`.

## <a name="BaseCommandCmd"></a>Class `BaseCommandCmd(cmd.Cmd)`

A `cmd.Cmd` subclass used to provide interactive use of a
command's subcommands.

The `BaseCommand.cmdloop()` class method instantiates an
instance of this and calls its `.cmdloop()` method
i.e. `cmd.Cmd.cmdloop`.

## <a name="BaseCommandOptions"></a>Class `BaseCommandOptions(cs.threads.HasThreadState)`

A base class for the `BaseCommand` `options` object.

This is the default class for the `self.options` object
available during `BaseCommand.run()`,
and available as the `BaseCommand.Options` attribute.

Any keyword arguments are applied as field updates to the instance.

It comes prefilled with:
* `.dry_run=False`
* `.force=False`
* `.quiet=False`
* `.ssh_exe='ssh'`
* `.verbose=False`
and a `.doit` property which is the inverse of `.dry_run`.

It is recommended that if `BaseCommand` subclasses use a
different type for their `Options` that it should be a
subclass of `BaseCommandOptions`.
Since `BaseCommandOptions` is a data class, this typically looks like:

    @dataclass
    class Options(BaseCommand.Options):
        ... optional extra fields etc ...

*`BaseCommandOptions.__call__(self, **updates)`*:
Calling the options object returns a context manager whose
value is a shallow copy of the options with any `suboptions` applied.

Example showing the semantics:

    >>> from cs.cmdutils import BaseCommandOptions
    >>> @dataclass
    ... class DemoOptions(BaseCommandOptions):
    ...   x: int = 0
    ...
    >>> options = DemoOptions(x=1)
    >>> assert options.x == 1
    >>> assert not options.verbose
    >>> with options(verbose=True) as subopts:
    ...     assert options is not subopts
    ...     assert options.x == 1
    ...     assert not options.verbose
    ...     assert subopts.x == 1
    ...     assert subopts.verbose
    ...
    >>> assert options.x == 1
    >>> assert not options.verbose

*`BaseCommandOptions.as_dict(self)`*:
Return the options as a `dict`.
This contains all the public attributes of `self`.

*`BaseCommandOptions.copy(self, **updates)`*:
Return a new instance of `BaseCommandOptions` (well, `type(self)`)
which is a shallow copy of the public attributes from `self.__dict__`.

Any keyword arguments are applied as attribute updates to the copy.

*`BaseCommandOptions.doit`*:
I usually use a `doit` flag, the inverse of `dry_run`.

*`BaseCommandOptions.fields_as_dict(self)`*:
Return the options' fields as a `dict`.
This contains all the field values of `self`.

*`BaseCommandOptions.getopt_spec_map(opt_specs_kw: Mapping, common_opt_specs=None)`*:
Return a 3-tuple of (shortopts,longopts,getopt_spec_map)` being:
- `shortopts`: the `getopt()` short options specification string
- `longopts`: the `getopts()` long option specification list
- `getopt_spec_map`: a mapping of `opt`->`OptionSpec`
  where `opt` is as from `opt,val` from `getopt()`
  and `opt_spec` is the associated `OptionSpec` instance

*`BaseCommandOptions.opt_spec_class`*

*`BaseCommandOptions.perthread_state`*

*`BaseCommandOptions.popopts(self, argv, **opt_specs_kw)`*:
Parse option switches from `argv`, a list of command line strings
with leading option switches and apply them to `self`.
Modify `argv` in place.

Example use in a `BaseCommand` `cmd_foo` method:

    def cmd_foo(self, argv):
        options = self.options
        options.popopts(
            c_='config',
            l='long',
            x='trace',
        )
        if self.options.dry_run:
            print("dry run!")

The expected options are specified by the keyword parameters
in `opt_specs`.
Each keyword name has the following semantics:
* options not starting with a letter may be preceeded by an underscore
  to allow use in the parameter list, for example `_1='once'`
  for a `-1` option setting the `once` option name
* a single letter name specifies a short option
  and a multiletter name specifies a long option
* options requiring an argument have a trailing underscore
* options not requiring an argument normally imply a value
  of `True`; if their synonym commences with a dash they will
  imply a value of `False`, for example `n='dry_run',y='-dry_run'`.

The `BaseCommand` class provides a `popopts` method
which is a shim for this method applied to its `.options`.
So common use in a command method usually looks like this:

    class SomeCommand(BaseCommand):

        def cmd_foo(self, argv):
            # accept a -j or --jobs options
            self.popopts(argv, jobs=1, j='jobs')
            print("jobs =", self.options.jobs)

The `self.options` object is preprovided as an instance of
the `self.Options` class, which is `BaseCommandOptions` by
default. There is presupplies support for some basic options
like `-v` for "verbose" and so forth, and a subcommand
need not describe these in a call to `self.options.popopts()`.

Example:

    >>> import os.path
    >>> from typing import Optional
    >>> @dataclass
    ... class DemoOptions(BaseCommandOptions):
    ...   all: bool = False
    ...   jobs: int = 1
    ...   number: int = 0
    ...   once: bool = False
    ...   path: Optional[str] = None
    ...   trace_exec: bool = False
    ...
    >>> options = DemoOptions()
    >>> argv = ['-1', '-v', '-y', '-j4', '--path=/foo', 'bah', '-x']
    >>> opt_dict = options.popopts(
    ...   argv,
    ...   _1='once',
    ...   a='all',
    ...   j_=('jobs',int),
    ...   x='-trace_exec',
    ...   y='-dry_run',
    ...   dry_run=None,
    ...   path_=(str, os.path.isabs, 'not an absolute path'),
    ...   verbose=None,
    ... )
    >>> opt_dict
    {'once': True, 'verbose': True, 'dry_run': False, 'jobs': 4, 'path': '/foo'}
    >>> options # doctest: +ELLIPSIS
    DemoOptions(cmd=None, dry_run=False, force=False, quiet=False, runstate_signals=(...), verbose=True, all=False, jobs=4, number=0, once=True, path='/foo', trace_exec=False)

*`BaseCommandOptions.update(self, **updates)`*:
Modify the options in place with the mapping `updates`.
It would be more normal to call the options in a `with` statement
as shown for `__call__`.

*`BaseCommandOptions.usage_options_format(headline='Options:', *, _common_opt_specs=None, **opt_specs_kw)`*:
Return an options paragraph describing `opt_specs_kw`.
or `''` if `opt_specs_kw` is empty.

## <a name="docmd"></a>`docmd(dofunc)`

Decorator for `cmd.Cmd` subclass methods
to supply some basic quality of service.

This decorator:
- wraps the function call in a `cs.pfx.Pfx` for context
- intercepts `getopt.GetoptError`s, issues a `warning`
  and runs `self.do_help` with the method name,
  then returns `None`
- intercepts other `Exception`s,
  issues an `exception` log message
  and returns `None`

The intended use is to decorate `cmd.Cmd` `do_`* methods:

    from cmd import Cmd
    from cs.cmdutils import docmd
    ...
    class MyCmd(Cmd):
        @docmd
        def do_something(...):
            ... do something ...

## <a name="OptionSpec"></a>Class `OptionSpec`

A class to support parsing an option value.

*`OptionSpec.__post_init__(self)`*:
Infer `field_name` and `help_text` if unspecified.

*`OptionSpec.add_argument(self, parser, options=None)`*:
Add this option to an `argparser`-style option parser.
The optional `options` parameter may be used to supply an
`Options` instance to provide a default value.

*`OptionSpec.from_opt_kw(opt_k: str, specs: Union[str, List, Tuple, NoneType])`*:
Factory to produce an `OptionSpec` from a `(key,specs)` 2-tuple
as from the `items()` from a `popopts()` call.

The `specs` is normally a list or tuple, but a bare string
will be promoted to a 1-element list containing the string.

The elements of `specs` are considered in order for:
- an identifier specifying the `arg_name`,
  optionally prepended with a dash to indicate an inverted option
- a help text about the option
- a callable to parse the option string value to obtain the actual value
- a callable to validate the option value
- a message for use when validation fails

*`OptionSpec.getopt_long`*:
The option specification for a getopt long option.
Return `None` if `self.opt_name` is only 1 character.

*`OptionSpec.getopt_opt`*:
The `opt` we expect from `opt,val=getopt(argv,...)`.

*`OptionSpec.getopt_short`*:
The option specification for a getopt short option.
Return `''` if `self.opt_name` is longer than 1 character.

*`OptionSpec.help_text_from_field_name(field_name)`*:
Compute an inferred `help_text` from an option `field_name`.

*`OptionSpec.needs_arg`*:
Whether we expect an argument: we have a `self.arg_name`.

*`OptionSpec.option_terse(self)`*:
Return the `"-x"` or `"--name"` option string (with the arg name if expected).

*`OptionSpec.option_usage(self)`*:
A 2 line usage entry for this option.
Example:

    -j jobs
      Job limit.

*`OptionSpec.parse_value(self, value)`*:
Parse `value` according to the spec.
Raises `GetoptError` for invalid values.

## <a name="popopts"></a>`popopts(*da, **dkw)`

A decorator to parse command line options from a `cmd_`*method*'s `argv`
and update `self.options`. This also updates the method's usage message.

Example:

    @popopts(x=('trace', 'Trace execution.'))
    def cmd_do_something(self, argv):
        """ Usage: {cmd} [-x] blah blah
              Do some thing to blah.
        """

This arranges for cmd_do_something to call `self.options.popopts(argv)`,
and updates the usage message with an "Options:" paragraph.

This avoids needing to manually enumerate the options in the
docstring usage and avoids explicitly calling `self.options.popopts`
inside the method.

## <a name="qvprint"></a>`qvprint(*print_a, quiet, verbose, **print_kw)`

Call `print()` if `options.verbose` and not `options.quiet`.

## <a name="split_usage"></a>`split_usage(doc: Optional[str], usage_marker='Usage:') -> Tuple[str, str, str]`

Extract a `"Usage:"`paragraph from a docstring
and return a 3-tuple of `(preusage,usage,postusage)`.

If the usage paragraph is not present `''` is returned as
the middle comonpent, otherwise it is the unindented usage
without the leading `"Usage:"`.

## <a name="SubCommand"></a>Class `SubCommand`

An implementation for a subcommand.

*`SubCommand.__call__(self, argv: List[str])`*:
Run the subcommand.

Parameters:
* `argv`: the command line arguments after the subcommand name

*`SubCommand.get_cmd(self) -> str`*:
Return the `cmd` string for this `SubCommand`,
derived from the subcommand's method name or class name
if `self.cmd` is not set.

*`SubCommand.get_subcmds(self)`*:
Return the names of `self.method`'s subcommands in lexical order.

*`SubCommand.get_subcommands(self)`*:
Return `self.method`'s mapping of subcommand name to `SubCommand`.

*`SubCommand.get_usage_format(self, show_common=False) -> str`*:
Return the usage format string for this subcommand.
*Note*: no leading "Usage:" prefix.
If `show_common` is true, include the `Common options:` paragraph.

*`SubCommand.get_usage_keywords(self, *, cmd: Optional[str] = None, usage_mapping: Optional[Mapping] = None) -> str`*:
Return a mapping to be used when formatting the usage format string.

This is an elaborate `ChainMap` of:
- the optional `cmd` or `self.get_cmd()`
- the optional `usage_mapping`
- `self.usage_mapping`
- `self.method.USAGE_KEYWORDS` if present
- the attributes of `self.command`
- the attributes of `type(self.command)`
- the attributes of the module for `type(self.command)`

*`SubCommand.has_subcommands`*:
Whether this `SubCommand`'s `.method` has subcommands.

*`SubCommand.instance`*:
An instance of the class for `self.method`.

*`SubCommand.short_subusages(self, subcmds: List[str], *, recurse=False, short=False)`*:
Return a list of tabulated one line subcommand summaries.

*`SubCommand.subusage_table(self, subcmds: List[str], *, recurse=False, short=False)`*:
Return rows for use with `cs.lex.tabulate`
for the short subusage listing.

*`SubCommand.usage_text(self, *, cmd=None, short: bool, recurse: bool = False, show_common: bool = False, show_subcmds: Union[bool, str, List[str], NoneType] = None, usage_mapping: Optional[Mapping] = None, seen_subcommands: Optional[Mapping] = None) -> str`*:
Return the filled out usage text for this subcommand.

## <a name="vprint"></a>`vprint(*print_a, **qvprint_kw)`

Call `print()` if `options.verbose`.
This is a compatibility shim for `qvprint()` with `quiet=False`.

# Release Log



*Release 20241222.1*:
* BaseCommand.cmd_info: use pformat instead of str.
* BaseCommand.cmd_repl: enumerate the options as top level names in the banner.
* If run as main programme, run a demo command.

*Release 20241222*:
BaseCommand.cmd_info: use compact=True with the pforat() call.

*Release 20241218*:
BaseCommand: add cmd_repl to the default subcomands.

*Release 20241212*:
SubCommand.short_subusages: use a single tabluate() table for the entire recursive listing, produces a much more readable short listing.

*Release 20241207*:
BaseCommandOptions.usage_options_format: support multiline help text via the new tabulate support.

*Release 20241206.1*:
SubComand.usage_text: normalise the show_subcmds to match the subcommands mapping.

*Release 20241206*:
* New @popopts decorator to run self.options.popopts and fill out the usage message.
* Add "-e ssh-command" and the .ssh_exe attribute to BaseCommandOptions.

*Release 20241122.2*:
* OptionSpec.getopt_long: fix construction of getopt long option specifications, lost during the recent refactor.
* Two other minor fixes.

*Release 20241122.1*:
* SubCommand.usage_format_parts: backport type annotation for older Pythons.
* BaseCommand.extract_usage: update parameters for usage_text().

*Release 20241122*:
* BaseCommand.cmd_help: new -l (long), -r (recurse) and -s (short, not long) options.
* A big rework of the help/usage output; still one rough edge left.
* BaseCommandOptions.popopts: infill with False instead of None for missing boolean options.
* SubCommand: a few new methods and properties to expose various operations.
* BaseCommand._prerun_setup: revert SUBCOMMAND_ARGV_DEFAULT to None, make a missing subcommand run "help -s" when there's no SUBCOMMAND_ARGV_DEFAULT.

*Release 20241119*:
* SubCommand.usage_text: small improvements and a fix.
* New BaseCommand.SubCommandClass attribute for the SubCommand subclass, supports using additional SubCommand subclasses for eg cs.djutils.

*Release 20241117*:
* _COMMON_OPT_SPECS: include a --dry-run option, alter for -n.
* SubCommand.usage_text: one line listing for common subcommands.

*Release 20241110*:
* Various fixes and enhancements to the usage text generation.
* BaseCommandOptions.COMMON_OPT_SPECS stuff, including inheritance and presentation in usage.
* BaseCommand.run: if self.run_context() yields not None, exit immediately with that value.
* Rationalise and improve OptionSpec.
* Supplant vprint with qvprint which honours quiet and verbose, provide vprint as a shim with a hardwired quiet=False.
* Make cmd_info the default subcommand and make some improvements.
* BaseCommandOptions: new fields_as_dict method, update copy() to start with fields_as_dict, overlay as_dict, overlay updates.
* OptionSpec: new add_argument(parser[,options]) method to add this option to an argparse style option parser (again, for the upcoming cs.djutils module).
* A heap of small things.

*Release 20241007*:
* BaseCommand: drop __init_subclass__, was doing too much to early.
* BaseCommand.__init__: no cmd and argv[0] ends with ".py" infer cmd from the class name.
* Other minor updates.

*Release 20241005*:
* BaseCommand: provide an options.runstate to allow the command to override the default (almost never happens).
* BaseCommand.popopts: fix reference to OptionSpec class.
* BaseCommand.run: put the try/except:CancellationError outside the self.run_context context manager call, as it can directly raise CancellationError.
* New vprint() function calling print() if options.verbose.

*Release 20240709*:
BaseCommand: support putting the top level Usage in the class docstring instead of as .USAGE_FORMAT, append full usage to the class docstring in `BaseCommand.__init_subclass__`.

*Release 20240630*:
* BaseCommand: make SUBCOMMAND_ARGV_DEFAULT be 'shell' for an interactive prompt, still a little unsure how sensible this is, aiming at the very cool submode stuff from the Cisco switch config command line.
* BaseCommandOptions: new as_dict() method.
* New SubCommand.usage_text() to compose the full usage text for this SubCommand.
* Many small improvements and internal refactors.

*Release 20240519*:
BaseCommand.run_context: attach the runstate to the options.

*Release 20240422*:
* BaseCommandOptions.popopts: return the dict from BaseCommand.popopts().
* BaseCommand.apply_preargv: apply the default options supported by self.options.
* BaseCommandOptions.update(mapping) method, useful for dropping subcommand-specific defaults onto the options ahead of the local popopts() call.

*Release 20240412*:
* BaseCommand.run_context: do not store .upd and .runstate on the options (it confuses options in subcommands and we have @uses_runstate and @uses_upd forthis anyway these days).
* BaseCommand.run_context: catch SIGQUIT, present the default handler as BaseCommand.handle_signal.

*Release 20240316*:
* New @uses_cmd_options decorator to provide an "options" parameter being the prevailing BaseCommandOptions instance.
* BaseCommandOptions.popopts: get common options from BaseCommandOptions.COMMON_OPT_SPECS.

*Release 20240211*:
* Include the first sentence of the subcommand description in the short help.
* BaseCommandOptions: move the runstate_signals into this directly.
* BaseCommand: move the run() options stuff into run_context() and have it work on a copy of the original options.
* BaseCommandCmd: implement get_names(), provide docstrings for the do_* attributes, thus help.
* BaseCommand.run_context: make runstate and upd keyword only parameters.

*Release 20240201*:
* BaseCommand.run: catch CancellationError and return 1.
* BaseCommandCmd.__getattr__: recognise EOF, exit and quit to terminate the cmdloop.

*Release 20231129*:
BaseCommandOptions: define a runstate field.

*Release 20230703*:
Small internal changes.

*Release 20230612*:
* BaseCommand.cmdloop: fix intro parameter.
* Other small fixes.

*Release 20230407*:
* BaseCommand: use @uses_runstate when preparing the command, store as self.options.runstate.
* Make BaseCommandOptions a data class.
* Drop any pretence at python 2 support, we're long past that.
* BaseCommand: new cmdloop method to run a cmd.Cmd instance to run subcommand interactively.
* BaseCommand: rename shell to repl, add cmd_shell to call cmdloop().
* Drop BaseCommand.apply_defaults in favour of the Options dataclass.
* BaseCommand: do setup_logging before initiating the Options instance.

*Release 20230212*:
* BaseCommand.run_context: update RunState support.
* BaseCommand.run_context: always be having an self.options.upd.

*Release 20230211*:
BaseCommand: new shell() method to present an interactive Python prompt for use by subclasses cmd_shell method if desired.

*Release 20221228*:
Move a lot of the context logic from BaseCommand.run to BaseCommand.run_context, which now must be correctly overridden in subclasses.

*Release 20220918*:
* BaseCommand.run_context: expand default signals to include SIGHUP, expose as BaseCommand.DEFAULT_SIGNALS.
* BaseCommand.run: pass in the subclass handle_signal method if present.

*Release 20220626*:
* BaseCommand.poparg: fix positional argument handling.
* BaseCommand.poparg: new unpop_on_error=False parameter to support pushing a bad argument back onto the front of the argument list.

*Release 20220606*:
BaseCommand.run: remove the Upd bodge, too annoying, now fixed in cs.upd I believe.

*Release 20220605*:
* BaseCommand: new popopts(argv,...) compact getopt wrapper.
* BaseCommand: new poparg(argv,...) compact validating argument consumer.
* BaseCommand: drop run_argv, provided no utility.
* BaseCommand.run: get the RunState signal list from self.options.runstate_signals.
* BaseCommand.apply_opts: support multiple individual options raising GetoptError, as I hate commands which abort at the first bad option.
* Assorted other small things.

*Release 20220429*:
* BaseCommand: fold dots in argv[0] into underscores, supports subcommands like "setup.py".
* BaseCommand: new popargv(argv[,help_text[,parse[,validate[,unvalidated_message]]]]) helper class method.
* BaseCommand: accept dashed-form of the underscored_form subcommand name.
* BaseCommand: new self.options.runstate_signals=SIGINT,SIGTERM specifying singals to catch-and-cancel, shuffle run() context managers.

*Release 20220318*:
BaseCommand.__init__: handle main() method in the New Scheme.

*Release 20220315*:
_BaseSubCommand.__init__: hook in the class USAGE_KEYWORDS for methods.

*Release 20220311*:
BaseCommand: big refactor of subcommand internals and make the "cmd_foo=FooCommand" implementation work properly.

*Release 20211208*:
BaseCommand: better handle an unknown subcommand.

*Release 20210927*:
* Usage: show only the per subcommand usage for in-subcommand GetoptError.
* Usage: show terse usage when the subcommand cannot be recognised.
* Usage: support bare -h, -help, --help.

*Release 20210913*:
New BaseCommand.apply_preargv method to gather special arguments before subcommands.

*Release 20210906*:
* BaseCommand.cmd_help: bugfix obsolete parameter list.
* BaseCommand.SUBCOMMAND_ARGV_DEFAULT: support a single str value, turn into list.

*Release 20210809*:
Bugfix BaseCommand.cmd_help for modern API.

*Release 20210731*:
* BaseCommand.run: apply optional keyword arguments to self.options during the run.
* Look for self.SUBCOMMAND_ARGV_DEFAULT if no subcommand is supplied.
* Bugfix case for "main" method and no "cmd_*" methods.
* Bugfix BaseCommand.cmd_help.

*Release 20210420*:
* BaseCommand.getopt_error_handler: replace error print() with warning().
* Docstring improvements.

*Release 20210407.1*:
BaseCommand: bugfix for __init_subclass__ docstring update.

*Release 20210407*:
* BaseCommand.__init_subclass__: behave sanely if the subclass has no initial __doc__.
* BaseCommand: new .run_argv convenience method, obviates the "def main" boilerplate.

*Release 20210404*:
BaseCommand subclasses: automatically add the main usage message to the subclass docstring.

*Release 20210306*:
* BREAKING CHANGE: rework BaseCommand as a more normal class instantiated with argv and with most methods being instance methods, getting the former `options` parameter from self.options.
* BaseCommand: provide default `apply_opt` and `apply_opts` methods; subclasses will generally just override the former.

*Release 20210123*:
BaseCommand: propagate the format mapping (cmd, USAGE_KEYWORDS) to the subusage generation.

*Release 20201102*:
* BaseCommand.cmd_help: supply usage only for "all commands", full docstring for specified commands.
* BaseCommand: honour presupplied options.log_level.
* BaseCommand.usage_text: handle missing USAGE_FORMAT better.
* BaseCommand.run: provide options.upd.
* BaseCommand subclasses may now override BaseCommand.OPTIONS_CLASS (default SimpleNamespace) in order to provide convenience methods on the options.
* BaseCommand.run: separate variable for subcmd with dash translated to underscore to match method names.
* Minor fixes.

*Release 20200615*:
BaseCommand.usage_text: do not mention the "help" command if it is the only subcommand (it won't be available if there are no other subcommands).

*Release 20200521.1*:
Fix DISTINFO.install_requires.

*Release 20200521*:
* BaseCommand.run: support using BaseCommand subclasses as cmd_* names to make it easy to nest BaseCommands.
* BaseCommand: new hack_postopts_argv method called after parsing the main command line options, for inferring subcommands or the like.
* BaseCommand: extract "Usage:" paragraphs from subcommand method docstrings to build the main usage message.
* BaseCommand: new cmd_help default command.
* Assorted bugfixes and small improvements.

*Release 20200318*:
* BaseCommand.run: make argv optional, get additional usage keywords from self.USAGE_KEYWORDS.
* @BaseCommand.add_usage_to_docstring: honour cls.USAGE_KEYWORDS.
* BaseCommand: do not require GETOPT_SPEC for commands with no defined options.
* BaseCommand.run: call cs.logutils.setup_logging.

*Release 20200229*:
Improve subcommand selection logic, replace StackableValues with stackattrs, drop `cmd` from arguments passed to main/cmd_* methods (present in `options`).

*Release 20200210*:
* New BaseCommand.add_usage_to_docstring class method to be called after class setup, to append the usage message to the class docstring.
* BaseCommand.run: remove spurious Pfx(cmd), as logutils does this for us already.

*Release 20190729*:
BaseCommand: support for a USAGE_FORMAT usage message format string and a getopt_error_handler method.

*Release 20190619.1*:
Another niggling docstring formatting fix.

*Release 20190619*:
Minor documentation updates.

*Release 20190617.2*:
Lint.

*Release 20190617.1*:
Initial release with @docmd decorator and alpha quality BaseCommand command line assistance class.

            

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    "_id": null,
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    "name": "cs-cmdutils",
    "maintainer": null,
    "docs_url": null,
    "requires_python": null,
    "maintainer_email": null,
    "keywords": "python2, python3",
    "author": null,
    "author_email": "Cameron Simpson <cs@cskk.id.au>",
    "download_url": "https://files.pythonhosted.org/packages/97/a2/f0f7c154c312678b9daca1a0b9e4bb7600525f294f678b2ad9a66340477a/cs_cmdutils-20241222.1.tar.gz",
    "platform": null,
    "description": "Convenience functions for working with the cmd stdlib module,\nthe BaseCommand class for constructing command line programmes,\nand other command line related stuff.\n\n*Latest release 20241222.1*:\n* BaseCommand.cmd_info: use pformat instead of str.\n* BaseCommand.cmd_repl: enumerate the options as top level names in the banner.\n* If run as main programme, run a demo command.\n\n## <a name=\"BaseCommand\"></a>Class `BaseCommand`\n\nA base class for handling nestable command lines.\n\nThis class provides the basic parse and dispatch mechanisms\nfor command lines.\nTo implement a command line\none instantiates a subclass of `BaseCommand`:\n\n    class MyCommand(BaseCommand):\n        GETOPT_SPEC = 'ab:c'\n        USAGE_FORMAT = r\"\"\"and provides either a `main` method if the command has no subcommands\nor a suite of `cmd_`*subcommand* methods, one per subcommand.\n\nRunning a command is done by:\n\n    MyCommand(argv).run()\n\nModules which implement a command line mode generally look like this:\n\n    ... imports etc ...\n    def main(argv=None, **run_kw):\n        \"\"\" The command line mode.\n        \"\"\"\n        return MyCommand(argv).run(**run_kw)\n    ... other code ...\n    class MyCommand(BaseCommand):\n    ... other code ...\n    if __name__ == '__main__':\n        sys.exit(main(sys.argv))\n\nInstances have a `self.options` attribute on which optional\nmodes are set,\navoiding conflict with the attributes of `self`.\n\nSubclasses with no subcommands\ngenerally just implement a `main(argv)` method.\n\nSubclasses with subcommands\nshould implement a `cmd_`*subcommand*`(argv)` instance method\nfor each subcommand.\nIf a subcommand is itself implemented using `BaseCommand`\nthen it can be a simple attribute:\n\n    cmd_subthing = SubThingCommand\n\nReturning to methods, if there is a paragraph in the method docstring\ncommencing with `Usage:` then that paragraph is incorporated\ninto the main usage message automatically.\nExample:\n\n    def cmd_ls(self, argv):\n        \"\"\" Usage: {cmd} [paths...]\n              Emit a listing for the named paths.\n\n            Further docstring non-usage information here.\n        \"\"\"\n        ... do the \"ls\" subcommand ...\n\nThe subclass is customised by overriding the following methods:\n* `apply_opt(opt,val)`:\n  apply an individual getopt global command line option\n  to `self.options`.\n* `apply_opts(opts)`:\n  apply the `opts` to `self.options`.\n  `opts` is an `(option,value)` sequence\n  as returned by `getopot.getopt`.\n  The default implementation iterates over these and calls `apply_opt`.\n* `run_context()`:\n  a context manager to provide setup or teardown actions\n  to occur before and after the command implementation respectively,\n  such as to open and close a database.\n* `cmd_`*subcmd*`(argv)`:\n  if the command line options are followed by an argument\n  whose value is *subcmd*,\n  then the method `cmd_`*subcmd*`(subcmd_argv)`\n  will be called where `subcmd_argv` contains the command line arguments\n  following *subcmd*.\n* `main(argv)`:\n  if there are no `cmd_`*subcmd*` methods then method `main(argv)`\n  will be called where `argv` contains the command line arguments.\n\nEditorial: why not arparse?\nPrimarily because when incorrectly invoked\nan argparse command line prints the help/usage messgae\nand aborts the whole programme with `SystemExit`.\nBut also, I find the whole argparse `add_argument` thing cumbersome.\n\nUsage summary:\n\n    Usage: base [common-options...] [-a] [-b bvalue] [-c] [--] arguments...\n        -a    Do it all.\n        -b    But using bvalue.\n        -c    The 'c' option!\n      \"\"\"\n      ...\n      Subcommands:\n        help [common-options...] [-l] [-s] [subcommand-names...]\n          Print help for subcommands.\n          This outputs the full help for the named subcommands,\n          or the short help for all subcommands if no names are specified.\n          Options:\n            -l  Long listing.\n            -r  Recurse into subcommands.\n            -s  Short listing.\n        info [common-options...] [field-names...]\n          Recite general information.\n          Explicit field names may be provided to override the default listing.\n        repl [common-options...]\n          Run a REPL (Read Evaluate Print Loop), an interactive Python prompt.\n          Options:\n            --banner banner  Banner.\n        shell [common-options...]\n          Run a command prompt via cmd.Cmd using this command's subcommands.\n\n*`BaseCommand.__init__(self, argv=None, *, cmd=None, options=None, **kw_options)`*:\nInitialise the command line.\nRaises `GetoptError` for unrecognised options.\n\nParameters:\n* `argv`:\n  optional command line arguments\n  including the main command name if `cmd` is not specified.\n  The default is `sys.argv`.\n  The contents of `argv` are copied,\n  permitting desctructive parsing of `argv`.\n* `cmd`:\n  optional keyword specifying the command name for context;\n  if this is not specified it is taken from `argv.pop(0)`.\n* `options`:\n  an optional keyword providing object for command state and context.\n  If not specified a new `self.Options` instance\n  is allocated for use as `options`.\n  The default `Options` class is `BaseCommandOptions`,\n  a dataclass with some prefilled attributes and properties\n  to aid use later.\nOther keyword arguments are applied to `self.options`\nas attributes.\n\nThe `cmd` and `argv` parameters have some fiddly semantics for convenience.\nThere are 3 basic ways to initialise:\n* `BaseCommand()`: `argv` comes from `sys.argv`\n  and the value for `cmd` is derived from `argv[0]`\n* `BaseCommand(argv)`: `argv` is the complete command line\n  including the command name and the value for `cmd` is\n  derived from `argv[0]`\n* `BaseCommand(argv, cmd=foo)`: `argv` is the command\n  arguments _after_ the command name and `cmd` is set to\n  `foo`\n\nThe command line arguments are parsed according to\nthe optional `GETOPT_SPEC` class attribute (default `''`).\nIf `getopt_spec` is not empty\nthen `apply_opts(opts)` is called\nto apply the supplied options to the state\nwhere `opts` is the return from `getopt.getopt(argv,getopt_spec)`.\n\nAfter the option parse,\nif the first command line argument *foo*\nhas a corresponding method `cmd_`*foo*\nthen that argument is removed from the start of `argv`\nand `self.cmd_`*foo*`(argv,options,cmd=`*foo*`)` is called\nand its value returned.\nOtherwise `self.main(argv,options)` is called\nand its value returned.\n\nIf the command implementation requires some setup or teardown\nthen this may be provided by the `run_context`\ncontext manager method,\ncalled with `cmd=`*subcmd* for subcommands\nand with `cmd=None` for `main`.\n\n*`BaseCommand.Options`*\n\n*`BaseCommand.SubCommandClass`*\n\n*`BaseCommand.apply_opt(self, opt, val)`*:\nHandle an individual global command line option.\n\nThis default implementation raises a `NotImplementedError`.\nIt only fires if `getopt` actually gathered arguments\nand would imply that a `GETOPT_SPEC` was supplied\nwithout an `apply_opt` or `apply_opts` method to implement the options.\n\n*`BaseCommand.apply_opts(self, opts)`*:\nApply command line options.\n\nSubclasses can override this\nbut it is usually easier to override `apply_opt(opt,val)`.\n\n*`BaseCommand.apply_preargv(self, argv)`*:\nDo any preparsing of `argv` before the subcommand/main-args.\nReturn the remaining arguments.\n\nThis default implementation applies the default options\nsupported by `self.options` (an instance of `self.Options`\nclass).\n\n*`BaseCommand.cmd_help(self, argv)`*:\nUsage: {cmd} [-l] [-s] [subcommand-names...]\nPrint help for subcommands.\nThis outputs the full help for the named subcommands,\nor the short help for all subcommands if no names are specified.\nOptions:\n  -l  Long listing.\n  -r  Recurse into subcommands.\n  -s  Short listing.\n\n*`BaseCommand.cmd_info(self, argv, *, field_names=None, skip_names=None)`*:\nUsage: {cmd} [field-names...]\n  Recite general information.\n  Explicit field names may be provided to override the default listing.\n\nThis default method recites the values from `self.options`,\nexcluding the basic fields from `BaseCommandOptions` other\nthan `cmd` and `dry_run`.\n\nThis base method provides two optional parameters to allow\nsubclasses to tune its behaviour:\n- `field_namees`: an explicit list of options attributes to print\n- `skip_names`: a list of option attributes to not print\n  if `field_names` is not specified; the default is the\n  field names of `BaseCommandOptions` excepting `cmd` and\n  `dry_run`\n\n*`BaseCommand.cmd_repl(self, argv)`*:\nUsage: {cmd}\nRun a REPL (Read Evaluate Print Loop), an interactive Python prompt.\nOptions:\n  --banner banner  Banner.\n\n*`BaseCommand.cmd_shell(*a, upd: Optional[cs.upd.Upd] = <function uses_upd.<locals>.<lambda> at 0x10473dda0>, **kw)`*:\nUsage: {cmd}\nRun a command prompt via cmd.Cmd using this command's subcommands.\n\n*`BaseCommand.cmdloop(self, intro=None)`*:\nUse `cmd.Cmd` to run a command loop which calls the `cmd_`* methods.\n\n*`BaseCommand.extract_usage(cmd=None)`*:\nExtract the `Usage:` paragraph from `cls__doc__` if present.\nReturn a 2-tuple of `(doc_without_usage,usage_text)`\nbeing the remaining docstring and a full usage message.\n\n*Note*: this actually sets `cls.USAGE_FORMAT` if that does\nnot already exist.\n\n*`BaseCommand.getopt_error_handler(cmd, options, e, usage, subcmd=None)`*:\nThe `getopt_error_handler` method\nis used to control the handling of `GetoptError`s raised\nduring the command line parse\nor during the `main` or `cmd_`*subcmd*` calls.\n\nThis default handler issues a warning containing the exception text,\nprints the usage message to standard error,\nand returns `True` to indicate that the error has been handled.\n\nThe handler is called with these parameters:\n* `cmd`: the command name\n* `options`: the `options` object\n* `e`: the `GetoptError` exception\n* `usage`: the command usage or `None` if this was not provided\n* `subcmd`: optional subcommand name;\n  if not `None`, is the name of the subcommand which caused the error\n\nIt returns a true value if the exception is considered handled,\nin which case the main `run` method returns 2.\nIt returns a false value if the exception is considered unhandled,\nin which case the main `run` method reraises the `GetoptError`.\n\nTo let the exceptions out unhandled\nthis can be overridden with a method which just returns `False`.\n\nOtherwise,\nthe handler may perform any suitable action\nand return `True` to contain the exception\nor `False` to cause the exception to be reraised.\n\n*`BaseCommand.handle_signal(self, sig, frame, *, runstate: Optional[cs.resources.RunState] = <function uses_runstate.<locals>.<lambda> at 0x10473d760>)`*:\nThe default signal handler, which cancels the default `RunState`.\n\n*`BaseCommand.has_subcommands()`*:\nTest whether the class defines additional subcommands.\n\n*`BaseCommand.method_cmdname(method_name: str)`*:\nThe `cmd` value from a method name.\n\n*`BaseCommand.poparg(argv: List[str], *specs, unpop_on_error: bool = False, opt_spec_class=None)`*:\nPop the leading argument off `argv` and parse it.\nReturn the parsed argument.\nRaises `getopt.GetoptError` on a missing or invalid argument.\n\nThis is expected to be used inside a `main` or `cmd_*`\ncommand handler method or inside `apply_preargv`.\n\nYou can just use:\n\n    value = argv.pop(0)\n\nbut this method provides conversion and valuation\nand a richer failure mode.\n\nParameters:\n* `argv`: the argument list, which is modified in place with `argv.pop(0)`\n* the argument list `argv` may be followed by some help text\n  and/or an argument parser function.\n* `validate`: an optional function to validate the parsed value;\n  this should return a true value if valid,\n  or return a false value or raise a `ValueError` if invalid\n* `unvalidated_message`: an optional message after `validate`\n  for values failing the validation\n* `unpop_on_error`: optional keyword parameter, default `False`;\n  if true then push the argument back onto the front of `argv`\n  if it fails to parse; `GetoptError` is still raised\n\nTypical use inside a `main` or `cmd_*` method might look like:\n\n    self.options.word = self.poparg(argv, int, \"a count value\")\n    self.options.word = self.poparg(\n        argv, int, \"a count value\",\n       lambda count: count > 0, \"count should be positive\")\n\nBecause it raises `GetoptError` on a bad argument\nthe normal usage message failure mode follows automatically.\n\nDemonstration:\n\n    >>> argv = ['word', '3', 'nine', '4']\n    >>> BaseCommand.poparg(argv, \"word to process\")\n    'word'\n    >>> BaseCommand.poparg(argv, int, \"count value\")\n    3\n    >>> BaseCommand.poparg(argv, float, \"length\")\n    Traceback (most recent call last):\n      ...\n    getopt.GetoptError: length 'nine': float('nine'): could not convert string to float: 'nine'\n    >>> BaseCommand.poparg(argv, float, \"width\", lambda width: width > 5)\n    Traceback (most recent call last):\n      ...\n    getopt.GetoptError: width '4': invalid value\n    >>> BaseCommand.poparg(argv, float, \"length\")\n    Traceback (most recent call last):\n      ...\n    getopt.GetoptError: length: missing argument\n    >>> argv = ['-5', 'zz']\n    >>> BaseCommand.poparg(argv, float, \"size\", lambda size: size > 0, \"size should be >0\")\n    Traceback (most recent call last):\n      ...\n    getopt.GetoptError: size '-5': size should be >0\n    >>> argv  # -5 was still consumed\n    ['zz']\n    >>> BaseCommand.poparg(argv, float, \"size2\", unpop_on_error=True)\n    Traceback (most recent call last):\n      ...\n    getopt.GetoptError: size2 'zz': float('zz'): could not convert string to float: 'zz'\n    >>> argv  # zz was pushed back\n    ['zz']\n\n*`BaseCommand.popopts(self, argv, options, **opt_specs)`*:\nOBSOLETE popopts\n\nA convenience shim which returns `self.options.popopts(argv,**opt_specs)`.\n\n*`BaseCommand.repl(self, *argv, banner=None, local=None)`*:\nRun an interactive Python prompt with some predefined local names.\nAka REPL (Read Evaluate Print Loop).\n\nParameters:\n* `argv`: any notional command line arguments\n* `banner`: optional banner string\n* `local`: optional local names mapping\n\nThe default `local` mapping is a `dict` containing:\n* `argv`: from `argv`\n* `options`: from `self.options`\n* `self`: from `self`\n* the attributes of `options`\n* the attributes of `self`\n\n*`BaseCommand.run(self, **kw_options)`*:\nRun a command.\nReturns the exit status of the command.\nMay raise `GetoptError` from subcommands.\n\nAny keyword arguments are used to override `self.options` attributes\nfor the duration of the run,\nfor example to presupply a shared `Upd` from an outer context.\n\nIf the first command line argument *foo*\nhas a corresponding method `cmd_`*foo*\nthen that argument is removed from the start of `argv`\nand `self.cmd_`*foo*`(cmd=`*foo*`)` is called\nand its value returned.\nOtherwise `self.main(argv)` is called\nand its value returned.\n\nIf the command implementation requires some setup or teardown\nthen this may be provided by the `run_context()`\ncontext manager method.\n\n*`BaseCommand.run_context(*a, upd: Optional[cs.upd.Upd] = <function uses_upd.<locals>.<lambda> at 0x10473d4e0>, **kw)`*:\nThe context manager which surrounds `main` or `cmd_`*subcmd*.\nNormally this will have a bare `yield`, but you can yield\na not `None` value to exit before the command, for example\nif the run setup fails.\n\nThis default does several things, and subclasses should\noverride it like this:\n\n    @contextmanager\n    def run_context(self):\n      with super().run_context():\n        try:\n          ... subclass context setup ...\n            yield\n        finally:\n          ... any unconditional cleanup ...\n\nThis base implementation does the following things:\n- provides a `self.options` which is a copy of the original\n  `self.options` so that it may freely be modified during the\n  command\n- provides a prevailing `RunState` as `self.options.runstate`\n  if one is not already present\n- provides a `cs.upd.Upd` context for status lines\n- catches `self.options.runstate_signals` and handles them\n  with `self.handle_signal`\n\n*`BaseCommand.subcommand`*\n\n*`BaseCommand.subcommand_usage_text(self, subcmd, usage_format_mapping=None, short=False)`*:\nReturn the usage text for a subcommand.\n\n*`BaseCommand.subcommands`*\n\n*`BaseCommand.usage_text(self, **subcommand_kw)`*:\nCompute the \"Usage:\" message for this class.\nParameters are as for `SubCommand.usage_text`.\n\n## <a name=\"BaseCommandCmd\"></a>Class `BaseCommandCmd(cmd.Cmd)`\n\nA `cmd.Cmd` subclass used to provide interactive use of a\ncommand's subcommands.\n\nThe `BaseCommand.cmdloop()` class method instantiates an\ninstance of this and calls its `.cmdloop()` method\ni.e. `cmd.Cmd.cmdloop`.\n\n## <a name=\"BaseCommandOptions\"></a>Class `BaseCommandOptions(cs.threads.HasThreadState)`\n\nA base class for the `BaseCommand` `options` object.\n\nThis is the default class for the `self.options` object\navailable during `BaseCommand.run()`,\nand available as the `BaseCommand.Options` attribute.\n\nAny keyword arguments are applied as field updates to the instance.\n\nIt comes prefilled with:\n* `.dry_run=False`\n* `.force=False`\n* `.quiet=False`\n* `.ssh_exe='ssh'`\n* `.verbose=False`\nand a `.doit` property which is the inverse of `.dry_run`.\n\nIt is recommended that if `BaseCommand` subclasses use a\ndifferent type for their `Options` that it should be a\nsubclass of `BaseCommandOptions`.\nSince `BaseCommandOptions` is a data class, this typically looks like:\n\n    @dataclass\n    class Options(BaseCommand.Options):\n        ... optional extra fields etc ...\n\n*`BaseCommandOptions.__call__(self, **updates)`*:\nCalling the options object returns a context manager whose\nvalue is a shallow copy of the options with any `suboptions` applied.\n\nExample showing the semantics:\n\n    >>> from cs.cmdutils import BaseCommandOptions\n    >>> @dataclass\n    ... class DemoOptions(BaseCommandOptions):\n    ...   x: int = 0\n    ...\n    >>> options = DemoOptions(x=1)\n    >>> assert options.x == 1\n    >>> assert not options.verbose\n    >>> with options(verbose=True) as subopts:\n    ...     assert options is not subopts\n    ...     assert options.x == 1\n    ...     assert not options.verbose\n    ...     assert subopts.x == 1\n    ...     assert subopts.verbose\n    ...\n    >>> assert options.x == 1\n    >>> assert not options.verbose\n\n*`BaseCommandOptions.as_dict(self)`*:\nReturn the options as a `dict`.\nThis contains all the public attributes of `self`.\n\n*`BaseCommandOptions.copy(self, **updates)`*:\nReturn a new instance of `BaseCommandOptions` (well, `type(self)`)\nwhich is a shallow copy of the public attributes from `self.__dict__`.\n\nAny keyword arguments are applied as attribute updates to the copy.\n\n*`BaseCommandOptions.doit`*:\nI usually use a `doit` flag, the inverse of `dry_run`.\n\n*`BaseCommandOptions.fields_as_dict(self)`*:\nReturn the options' fields as a `dict`.\nThis contains all the field values of `self`.\n\n*`BaseCommandOptions.getopt_spec_map(opt_specs_kw: Mapping, common_opt_specs=None)`*:\nReturn a 3-tuple of (shortopts,longopts,getopt_spec_map)` being:\n- `shortopts`: the `getopt()` short options specification string\n- `longopts`: the `getopts()` long option specification list\n- `getopt_spec_map`: a mapping of `opt`->`OptionSpec`\n  where `opt` is as from `opt,val` from `getopt()`\n  and `opt_spec` is the associated `OptionSpec` instance\n\n*`BaseCommandOptions.opt_spec_class`*\n\n*`BaseCommandOptions.perthread_state`*\n\n*`BaseCommandOptions.popopts(self, argv, **opt_specs_kw)`*:\nParse option switches from `argv`, a list of command line strings\nwith leading option switches and apply them to `self`.\nModify `argv` in place.\n\nExample use in a `BaseCommand` `cmd_foo` method:\n\n    def cmd_foo(self, argv):\n        options = self.options\n        options.popopts(\n            c_='config',\n            l='long',\n            x='trace',\n        )\n        if self.options.dry_run:\n            print(\"dry run!\")\n\nThe expected options are specified by the keyword parameters\nin `opt_specs`.\nEach keyword name has the following semantics:\n* options not starting with a letter may be preceeded by an underscore\n  to allow use in the parameter list, for example `_1='once'`\n  for a `-1` option setting the `once` option name\n* a single letter name specifies a short option\n  and a multiletter name specifies a long option\n* options requiring an argument have a trailing underscore\n* options not requiring an argument normally imply a value\n  of `True`; if their synonym commences with a dash they will\n  imply a value of `False`, for example `n='dry_run',y='-dry_run'`.\n\nThe `BaseCommand` class provides a `popopts` method\nwhich is a shim for this method applied to its `.options`.\nSo common use in a command method usually looks like this:\n\n    class SomeCommand(BaseCommand):\n\n        def cmd_foo(self, argv):\n            # accept a -j or --jobs options\n            self.popopts(argv, jobs=1, j='jobs')\n            print(\"jobs =\", self.options.jobs)\n\nThe `self.options` object is preprovided as an instance of\nthe `self.Options` class, which is `BaseCommandOptions` by\ndefault. There is presupplies support for some basic options\nlike `-v` for \"verbose\" and so forth, and a subcommand\nneed not describe these in a call to `self.options.popopts()`.\n\nExample:\n\n    >>> import os.path\n    >>> from typing import Optional\n    >>> @dataclass\n    ... class DemoOptions(BaseCommandOptions):\n    ...   all: bool = False\n    ...   jobs: int = 1\n    ...   number: int = 0\n    ...   once: bool = False\n    ...   path: Optional[str] = None\n    ...   trace_exec: bool = False\n    ...\n    >>> options = DemoOptions()\n    >>> argv = ['-1', '-v', '-y', '-j4', '--path=/foo', 'bah', '-x']\n    >>> opt_dict = options.popopts(\n    ...   argv,\n    ...   _1='once',\n    ...   a='all',\n    ...   j_=('jobs',int),\n    ...   x='-trace_exec',\n    ...   y='-dry_run',\n    ...   dry_run=None,\n    ...   path_=(str, os.path.isabs, 'not an absolute path'),\n    ...   verbose=None,\n    ... )\n    >>> opt_dict\n    {'once': True, 'verbose': True, 'dry_run': False, 'jobs': 4, 'path': '/foo'}\n    >>> options # doctest: +ELLIPSIS\n    DemoOptions(cmd=None, dry_run=False, force=False, quiet=False, runstate_signals=(...), verbose=True, all=False, jobs=4, number=0, once=True, path='/foo', trace_exec=False)\n\n*`BaseCommandOptions.update(self, **updates)`*:\nModify the options in place with the mapping `updates`.\nIt would be more normal to call the options in a `with` statement\nas shown for `__call__`.\n\n*`BaseCommandOptions.usage_options_format(headline='Options:', *, _common_opt_specs=None, **opt_specs_kw)`*:\nReturn an options paragraph describing `opt_specs_kw`.\nor `''` if `opt_specs_kw` is empty.\n\n## <a name=\"docmd\"></a>`docmd(dofunc)`\n\nDecorator for `cmd.Cmd` subclass methods\nto supply some basic quality of service.\n\nThis decorator:\n- wraps the function call in a `cs.pfx.Pfx` for context\n- intercepts `getopt.GetoptError`s, issues a `warning`\n  and runs `self.do_help` with the method name,\n  then returns `None`\n- intercepts other `Exception`s,\n  issues an `exception` log message\n  and returns `None`\n\nThe intended use is to decorate `cmd.Cmd` `do_`* methods:\n\n    from cmd import Cmd\n    from cs.cmdutils import docmd\n    ...\n    class MyCmd(Cmd):\n        @docmd\n        def do_something(...):\n            ... do something ...\n\n## <a name=\"OptionSpec\"></a>Class `OptionSpec`\n\nA class to support parsing an option value.\n\n*`OptionSpec.__post_init__(self)`*:\nInfer `field_name` and `help_text` if unspecified.\n\n*`OptionSpec.add_argument(self, parser, options=None)`*:\nAdd this option to an `argparser`-style option parser.\nThe optional `options` parameter may be used to supply an\n`Options` instance to provide a default value.\n\n*`OptionSpec.from_opt_kw(opt_k: str, specs: Union[str, List, Tuple, NoneType])`*:\nFactory to produce an `OptionSpec` from a `(key,specs)` 2-tuple\nas from the `items()` from a `popopts()` call.\n\nThe `specs` is normally a list or tuple, but a bare string\nwill be promoted to a 1-element list containing the string.\n\nThe elements of `specs` are considered in order for:\n- an identifier specifying the `arg_name`,\n  optionally prepended with a dash to indicate an inverted option\n- a help text about the option\n- a callable to parse the option string value to obtain the actual value\n- a callable to validate the option value\n- a message for use when validation fails\n\n*`OptionSpec.getopt_long`*:\nThe option specification for a getopt long option.\nReturn `None` if `self.opt_name` is only 1 character.\n\n*`OptionSpec.getopt_opt`*:\nThe `opt` we expect from `opt,val=getopt(argv,...)`.\n\n*`OptionSpec.getopt_short`*:\nThe option specification for a getopt short option.\nReturn `''` if `self.opt_name` is longer than 1 character.\n\n*`OptionSpec.help_text_from_field_name(field_name)`*:\nCompute an inferred `help_text` from an option `field_name`.\n\n*`OptionSpec.needs_arg`*:\nWhether we expect an argument: we have a `self.arg_name`.\n\n*`OptionSpec.option_terse(self)`*:\nReturn the `\"-x\"` or `\"--name\"` option string (with the arg name if expected).\n\n*`OptionSpec.option_usage(self)`*:\nA 2 line usage entry for this option.\nExample:\n\n    -j jobs\n      Job limit.\n\n*`OptionSpec.parse_value(self, value)`*:\nParse `value` according to the spec.\nRaises `GetoptError` for invalid values.\n\n## <a name=\"popopts\"></a>`popopts(*da, **dkw)`\n\nA decorator to parse command line options from a `cmd_`*method*'s `argv`\nand update `self.options`. This also updates the method's usage message.\n\nExample:\n\n    @popopts(x=('trace', 'Trace execution.'))\n    def cmd_do_something(self, argv):\n        \"\"\" Usage: {cmd} [-x] blah blah\n              Do some thing to blah.\n        \"\"\"\n\nThis arranges for cmd_do_something to call `self.options.popopts(argv)`,\nand updates the usage message with an \"Options:\" paragraph.\n\nThis avoids needing to manually enumerate the options in the\ndocstring usage and avoids explicitly calling `self.options.popopts`\ninside the method.\n\n## <a name=\"qvprint\"></a>`qvprint(*print_a, quiet, verbose, **print_kw)`\n\nCall `print()` if `options.verbose` and not `options.quiet`.\n\n## <a name=\"split_usage\"></a>`split_usage(doc: Optional[str], usage_marker='Usage:') -> Tuple[str, str, str]`\n\nExtract a `\"Usage:\"`paragraph from a docstring\nand return a 3-tuple of `(preusage,usage,postusage)`.\n\nIf the usage paragraph is not present `''` is returned as\nthe middle comonpent, otherwise it is the unindented usage\nwithout the leading `\"Usage:\"`.\n\n## <a name=\"SubCommand\"></a>Class `SubCommand`\n\nAn implementation for a subcommand.\n\n*`SubCommand.__call__(self, argv: List[str])`*:\nRun the subcommand.\n\nParameters:\n* `argv`: the command line arguments after the subcommand name\n\n*`SubCommand.get_cmd(self) -> str`*:\nReturn the `cmd` string for this `SubCommand`,\nderived from the subcommand's method name or class name\nif `self.cmd` is not set.\n\n*`SubCommand.get_subcmds(self)`*:\nReturn the names of `self.method`'s subcommands in lexical order.\n\n*`SubCommand.get_subcommands(self)`*:\nReturn `self.method`'s mapping of subcommand name to `SubCommand`.\n\n*`SubCommand.get_usage_format(self, show_common=False) -> str`*:\nReturn the usage format string for this subcommand.\n*Note*: no leading \"Usage:\" prefix.\nIf `show_common` is true, include the `Common options:` paragraph.\n\n*`SubCommand.get_usage_keywords(self, *, cmd: Optional[str] = None, usage_mapping: Optional[Mapping] = None) -> str`*:\nReturn a mapping to be used when formatting the usage format string.\n\nThis is an elaborate `ChainMap` of:\n- the optional `cmd` or `self.get_cmd()`\n- the optional `usage_mapping`\n- `self.usage_mapping`\n- `self.method.USAGE_KEYWORDS` if present\n- the attributes of `self.command`\n- the attributes of `type(self.command)`\n- the attributes of the module for `type(self.command)`\n\n*`SubCommand.has_subcommands`*:\nWhether this `SubCommand`'s `.method` has subcommands.\n\n*`SubCommand.instance`*:\nAn instance of the class for `self.method`.\n\n*`SubCommand.short_subusages(self, subcmds: List[str], *, recurse=False, short=False)`*:\nReturn a list of tabulated one line subcommand summaries.\n\n*`SubCommand.subusage_table(self, subcmds: List[str], *, recurse=False, short=False)`*:\nReturn rows for use with `cs.lex.tabulate`\nfor the short subusage listing.\n\n*`SubCommand.usage_text(self, *, cmd=None, short: bool, recurse: bool = False, show_common: bool = False, show_subcmds: Union[bool, str, List[str], NoneType] = None, usage_mapping: Optional[Mapping] = None, seen_subcommands: Optional[Mapping] = None) -> str`*:\nReturn the filled out usage text for this subcommand.\n\n## <a name=\"vprint\"></a>`vprint(*print_a, **qvprint_kw)`\n\nCall `print()` if `options.verbose`.\nThis is a compatibility shim for `qvprint()` with `quiet=False`.\n\n# Release Log\n\n\n\n*Release 20241222.1*:\n* BaseCommand.cmd_info: use pformat instead of str.\n* BaseCommand.cmd_repl: enumerate the options as top level names in the banner.\n* If run as main programme, run a demo command.\n\n*Release 20241222*:\nBaseCommand.cmd_info: use compact=True with the pforat() call.\n\n*Release 20241218*:\nBaseCommand: add cmd_repl to the default subcomands.\n\n*Release 20241212*:\nSubCommand.short_subusages: use a single tabluate() table for the entire recursive listing, produces a much more readable short listing.\n\n*Release 20241207*:\nBaseCommandOptions.usage_options_format: support multiline help text via the new tabulate support.\n\n*Release 20241206.1*:\nSubComand.usage_text: normalise the show_subcmds to match the subcommands mapping.\n\n*Release 20241206*:\n* New @popopts decorator to run self.options.popopts and fill out the usage message.\n* Add \"-e ssh-command\" and the .ssh_exe attribute to BaseCommandOptions.\n\n*Release 20241122.2*:\n* OptionSpec.getopt_long: fix construction of getopt long option specifications, lost during the recent refactor.\n* Two other minor fixes.\n\n*Release 20241122.1*:\n* SubCommand.usage_format_parts: backport type annotation for older Pythons.\n* BaseCommand.extract_usage: update parameters for usage_text().\n\n*Release 20241122*:\n* BaseCommand.cmd_help: new -l (long), -r (recurse) and -s (short, not long) options.\n* A big rework of the help/usage output; still one rough edge left.\n* BaseCommandOptions.popopts: infill with False instead of None for missing boolean options.\n* SubCommand: a few new methods and properties to expose various operations.\n* BaseCommand._prerun_setup: revert SUBCOMMAND_ARGV_DEFAULT to None, make a missing subcommand run \"help -s\" when there's no SUBCOMMAND_ARGV_DEFAULT.\n\n*Release 20241119*:\n* SubCommand.usage_text: small improvements and a fix.\n* New BaseCommand.SubCommandClass attribute for the SubCommand subclass, supports using additional SubCommand subclasses for eg cs.djutils.\n\n*Release 20241117*:\n* _COMMON_OPT_SPECS: include a --dry-run option, alter for -n.\n* SubCommand.usage_text: one line listing for common subcommands.\n\n*Release 20241110*:\n* Various fixes and enhancements to the usage text generation.\n* BaseCommandOptions.COMMON_OPT_SPECS stuff, including inheritance and presentation in usage.\n* BaseCommand.run: if self.run_context() yields not None, exit immediately with that value.\n* Rationalise and improve OptionSpec.\n* Supplant vprint with qvprint which honours quiet and verbose, provide vprint as a shim with a hardwired quiet=False.\n* Make cmd_info the default subcommand and make some improvements.\n* BaseCommandOptions: new fields_as_dict method, update copy() to start with fields_as_dict, overlay as_dict, overlay updates.\n* OptionSpec: new add_argument(parser[,options]) method to add this option to an argparse style option parser (again, for the upcoming cs.djutils module).\n* A heap of small things.\n\n*Release 20241007*:\n* BaseCommand: drop __init_subclass__, was doing too much to early.\n* BaseCommand.__init__: no cmd and argv[0] ends with \".py\" infer cmd from the class name.\n* Other minor updates.\n\n*Release 20241005*:\n* BaseCommand: provide an options.runstate to allow the command to override the default (almost never happens).\n* BaseCommand.popopts: fix reference to OptionSpec class.\n* BaseCommand.run: put the try/except:CancellationError outside the self.run_context context manager call, as it can directly raise CancellationError.\n* New vprint() function calling print() if options.verbose.\n\n*Release 20240709*:\nBaseCommand: support putting the top level Usage in the class docstring instead of as .USAGE_FORMAT, append full usage to the class docstring in `BaseCommand.__init_subclass__`.\n\n*Release 20240630*:\n* BaseCommand: make SUBCOMMAND_ARGV_DEFAULT be 'shell' for an interactive prompt, still a little unsure how sensible this is, aiming at the very cool submode stuff from the Cisco switch config command line.\n* BaseCommandOptions: new as_dict() method.\n* New SubCommand.usage_text() to compose the full usage text for this SubCommand.\n* Many small improvements and internal refactors.\n\n*Release 20240519*:\nBaseCommand.run_context: attach the runstate to the options.\n\n*Release 20240422*:\n* BaseCommandOptions.popopts: return the dict from BaseCommand.popopts().\n* BaseCommand.apply_preargv: apply the default options supported by self.options.\n* BaseCommandOptions.update(mapping) method, useful for dropping subcommand-specific defaults onto the options ahead of the local popopts() call.\n\n*Release 20240412*:\n* BaseCommand.run_context: do not store .upd and .runstate on the options (it confuses options in subcommands and we have @uses_runstate and @uses_upd forthis anyway these days).\n* BaseCommand.run_context: catch SIGQUIT, present the default handler as BaseCommand.handle_signal.\n\n*Release 20240316*:\n* New @uses_cmd_options decorator to provide an \"options\" parameter being the prevailing BaseCommandOptions instance.\n* BaseCommandOptions.popopts: get common options from BaseCommandOptions.COMMON_OPT_SPECS.\n\n*Release 20240211*:\n* Include the first sentence of the subcommand description in the short help.\n* BaseCommandOptions: move the runstate_signals into this directly.\n* BaseCommand: move the run() options stuff into run_context() and have it work on a copy of the original options.\n* BaseCommandCmd: implement get_names(), provide docstrings for the do_* attributes, thus 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