| Name | rust-result JSON |
| Version |
0.2.1
JSON |
| download |
| home_page | None |
| Summary | None |
| upload_time | 2024-09-23 09:43:33 |
| maintainer | None |
| docs_url | None |
| author | Ole Kliemann |
| requires_python | >=3.10 |
| license | MIT |
| keywords |
|
| VCS |
|
| bugtrack_url |
|
| requirements |
No requirements were recorded.
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No Travis.
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No coveralls.
|
# rust-result
More radical approach to Rust's `std::result` in Python.
## Motivation
I do not want exceptions in my code.
Rust has this figured out quite neatly
by essentially revolving around two pathways for errors:
A possible error condition is either one that has no prospect of being handled
-- then the program should terminate -- or it is one that could be handled --
then it has to be handled or explicitly ignored.
This concept is replicated here by using `AssertionError` to emulate Rust's `panic!`,
mapping all unhandled exceptions to `AssertionError`
and providing a Rust-like `result` type to signal error conditions that do not need to terminate
the program.
## Documentation
```python
from rust_result import Ok, Err, returns_result
@returns_result()
def read_file():
with open('/this/path/is/invalid') as f:
return Ok(f.read())
result = func()
```
This will raise an `AssertionError` due to an unhandled exception.
But if you specify the exceptions you expect, you can handle the error:
```python
@returns_result(FileNotFoundError)
def read_file():
with open('/this/path/is/invalid') as f:
return Ok(f.read())
result = func()
if result.is_ok():
print(f'File content: {result.unwrap()}')
else:
print(f'Error: {result.unwrap_err()}')
```
Or -- if you are feeling fancy -- you can do pattern matching:
```python
@returns_result(FileNotFoundError)
def read_file():
with open('/this/path/is/invalid') as f:
return f.read()
result = read_file()
match result:
case Ok(v):
print(f'File content: {v}')
case Err(e):
print(f'Error: {e}')
```
And even fancier:
```python
data = [
{ 'foo': 'value-1' },
{ 'bar': 'value-2' }
]
@returns_result(IndexError, KeyError)
def retrieve_record_entry_backend(index, key):
return Ok(data[index][key])
def retrieve_record_entry(index, key):
match retrieve_record_entry_backend(index, key):
case Ok(v):
print(f'Retrieved: {v}')
case Err(IndexError()):
print(f'No such record: {index}')
case Err(KeyError()):
print(f'No entry `{key}` in record {index}')
retrieve_record_entry(2, 'foo') # No such record: 2
retrieve_record_entry(1, 'foo') # No entry `foo` in record 1
retrieve_record_entry(1, 'bar') # Retrieved: value-2
```
## Similar Projects
For a less extreme approach on Rust's result type, see:
* [https://github.com/rustedpy/result](https://github.com/rustedpy/result)
* [https://github.com/felixhammerl/resultify](https://github.com/felixhammerl/resultify)
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"description": "# rust-result\n\nMore radical approach to Rust's `std::result` in Python.\n\n## Motivation\n\nI do not want exceptions in my code.\nRust has this figured out quite neatly\nby essentially revolving around two pathways for errors:\nA possible error condition is either one that has no prospect of being handled\n-- then the program should terminate -- or it is one that could be handled --\nthen it has to be handled or explicitly ignored.\n\nThis concept is replicated here by using `AssertionError` to emulate Rust's `panic!`,\nmapping all unhandled exceptions to `AssertionError`\nand providing a Rust-like `result` type to signal error conditions that do not need to terminate\nthe program.\n\n## Documentation\n\n```python\nfrom rust_result import Ok, Err, returns_result\n\n@returns_result()\ndef read_file():\n with open('/this/path/is/invalid') as f:\n return Ok(f.read())\n\nresult = func()\n```\nThis will raise an `AssertionError` due to an unhandled exception.\n\nBut if you specify the exceptions you expect, you can handle the error:\n```python\n@returns_result(FileNotFoundError)\ndef read_file():\n with open('/this/path/is/invalid') as f:\n return Ok(f.read())\n\nresult = func()\nif result.is_ok():\n print(f'File content: {result.unwrap()}')\nelse:\n print(f'Error: {result.unwrap_err()}')\n```\n\nOr -- if you are feeling fancy -- you can do pattern matching:\n```python\n@returns_result(FileNotFoundError)\ndef read_file():\n with open('/this/path/is/invalid') as f:\n return f.read()\n\nresult = read_file()\nmatch result:\n case Ok(v):\n print(f'File content: {v}')\n case Err(e):\n print(f'Error: {e}')\n```\n\nAnd even fancier:\n```python\ndata = [\n { 'foo': 'value-1' },\n { 'bar': 'value-2' }\n]\n\n@returns_result(IndexError, KeyError)\ndef retrieve_record_entry_backend(index, key):\n return Ok(data[index][key])\n\ndef retrieve_record_entry(index, key):\n match retrieve_record_entry_backend(index, key):\n case Ok(v):\n print(f'Retrieved: {v}')\n case Err(IndexError()):\n print(f'No such record: {index}')\n case Err(KeyError()):\n print(f'No entry `{key}` in record {index}')\n\nretrieve_record_entry(2, 'foo') # No such record: 2\nretrieve_record_entry(1, 'foo') # No entry `foo` in record 1\nretrieve_record_entry(1, 'bar') # Retrieved: value-2\n```\n\n## Similar Projects\n\nFor a less extreme approach on Rust's result type, see:\n\n* [https://github.com/rustedpy/result](https://github.com/rustedpy/result)\n* [https://github.com/felixhammerl/resultify](https://github.com/felixhammerl/resultify)\n",
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