New submission from Yurii Karabas <[email protected]>:
In the current python codebases, there are a lot of decorators with parameters,
and their code in most cases contains a lot of code boilerplates. The purpose
of this issue is to add `decorator_with_params` function to `functools` module.
This function will allow using a wrapped function as a simple decorator and
decorator with parameter.
I believe the real example will bring more context, for instance,
`typing._tp_cache` function can be rewritten from:
```
def _tp_cache(func=None, /, *, typed=False):
"""Internal wrapper caching __getitem__ of generic types with a fallback to
original function for non-hashable arguments.
"""
def decorator(func):
cached = functools.lru_cache(typed=typed)(func)
_cleanups.append(cached.cache_clear)
@functools.wraps(func)
def inner(*args, **kwds):
try:
return cached(*args, **kwds)
except TypeError:
pass
return func(*args, **kwds)
return inner
if func is not None:
return decorator(func)
return decorator
```
To
```
@decorator_with_params
def _tp_cache(func=None, /, *, typed=False):
"""Internal wrapper caching __getitem__ of generic types with a fallback to
original function for non-hashable arguments.
"""
cached = functools.lru_cache(typed=typed)(func)
_cleanups.append(cached.cache_clear)
@functools.wraps(func)
def inner(*args, **kwds):
try:
return cached(*args, **kwds)
except TypeError:
pass # All real errors (not unhashable args) are raised below.
return func(*args, **kwds)
return inner
```
And `_tp_cache` can be used as:
```
@_tp_cache(typed=True)
def __getitem__(self, parameters):
return self._getitem(self, parameters)
...
@_tp_cache
def __getitem__(self, parameters):
return self._getitem(self, parameters)
```
Proposed implementation is quite simple (I used it in a lot of projects):
```
def decorator_with_params(deco):
@wraps(deco)
def decorator(func=None, /, *args, **kwargs):
if func is not None:
return deco(func, *args, **kwargs)
def wrapper(f):
return deco(f, *args, **kwargs)
return wrapper
return decorator
```
I believe it will be a great enhancement for the Python standard library and
will save such important indentations.
----------
components: Library (Lib)
messages: 381773
nosy: uriyyo
priority: normal
severity: normal
status: open
title: Add decorator_with_params function to functools module
type: enhancement
versions: Python 3.10
_______________________________________
Python tracker <[email protected]>
<https://bugs.python.org/issue42455>
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