Is there a non-performance regressive way to proxy attr access to func.__name__ of the partial function (or method; Callable)?
Would this affect documentation generation tools like e.g. sphinx-spidoc, which IIRC use __name__ and probably now __qualname__ for generating argspecs in RST for HTML and LaTeX? - https://docs.python.org/3/library/inspect.html - functions and methods have __name__ and __qualname__ - see: sphinx.utils.inspect - https://docs.python.org/3/library/functools.html#functools.partial - https://docs.python.org/3/library/functools.html#functools.partialmethod - https://docs.python.org/3/library/functools.html#partial-objects > partial Objects¶ > partial objects are callable objects created by partial(). They have three read-only attributes: > > partial.func > A callable object or function. Calls to the partial object will be forwarded to func with new arguments and keywords. > > partial.args > The leftmost positional arguments that will be prepended to the positional arguments provided to a partial object call. > > partial.keywords > The keyword arguments that will be supplied when the partial object is called. > partial objects are like function objects in that they are callable, weak referencable, and can have attributes. There are some important differences. For instance, the __name__ and __doc__ attributes are not created automatically. Also, partial objects defined in classes behave like static methods and do not transform into bound methods during instance attribute look-up. - https://www.sphinx-doc.org/en/master/man/sphinx-apidoc.html - https://www.sphinx-doc.org/en/master/_modules/sphinx/ext/autodoc.html : 18 references to __qualname__, https://github.com/sphinx-doc/sphinx/blob/5.x/sphinx/util/inspect.py#L49-L66 : ```python def unwrap_all(obj: Any, *, stop: Optional[Callable] = None) -> Any: """ Get an original object from wrapped object (unwrapping partials, wrapped functions, and other decorators). """ while True: if stop and stop(obj): return obj elif ispartial(obj): obj = obj.func elif inspect.isroutine(obj) and hasattr(obj, '__wrapped__'): obj = obj.__wrapped__ # type: ignore elif isclassmethod(obj): obj = obj.__func__ elif isstaticmethod(obj): obj = obj.__func__ else: return obj ``` From https://github.com/sphinx-doc/sphinx/blob/5.x/sphinx/util/inspect.py#L173-L186 : ```python def unpartial(obj: Any) -> Any: """Get an original object from partial object. This returns given object itself if not partial. """ while ispartial(obj): obj = obj.func return obj def ispartial(obj: Any) -> bool: """Check if the object is partial.""" return isinstance(obj, (partial, partialmethod)) ``` - https://github.com/sphinx-doc/sphinx/issues/4826#issuecomment-808699254 https://docs.python.org/3/library/stdtypes.html#definition.__name__ https://docs.python.org/3/reference/datamodel.html#the-standard-type-hierarchy > Callable types > User defined functions does list both __name__ and __qualname__ Is there a non-performance regressive way to proxy attr access to __name__ of the partially curried (?) function? >From "PEP 3155 – Qualified name for classes and functions" https://peps.python.org/pep-3155/#limitations : > ### Limitations > With nested functions (and classes defined inside functions), the dotted path will not be walkable programmatically as a function’s namespace is not available from the outside. It will still be more helpful to the human reader than the bare __name__. > > As the __name__ attribute, the __qualname__ attribute is computed statically and it will not automatically follow rebinding. From https://wrapt.readthedocs.io/en/latest/wrappers.html#proxy-object-attributes : > Proxy Object Attributes > When an attempt is made to access an attribute from the proxy, the same named attribute would in normal circumstances be accessed from the wrapped object. When updating an attributes value, or deleting the attribute, that change will also be reflected in the wrapped object. >From https://docs.python.org/3/library/weakref.html#weakref.proxy : > weakref.proxy(object[, callback])¶ > Return a proxy to object which uses a weak reference. This supports use of the proxy in most contexts instead of requiring the explicit dereferencing used with weak reference objects. The returned object will have a type of either ProxyType or CallableProxyType, depending on whether object is callable. Proxy objects are not hashable regardless of the referent; this avoids a number of problems related to their fundamentally mutable nature, and prevent their use as dictionary keys. callback is the same as the parameter of the same name to the ref() function. On Tue, Aug 30, 2022, 1:14 AM Charles Machalow <csm10...@gmail.com> wrote: > 1: There are cases where one may need the __name__/__qualname__ of a given > callable. If someone uses partial to create a new callable, there is no > __name__/__qualname__ given. In my particular case, I'm logging what > callback function is passed to a different function... if someone uses > partial, there is no __name__/__qualname__ which leads to a current > traceback... of course i can work around it but still was an odd case to me. > > Per the docs on functools.partial: > "Return a new partial object which when called will behave like func > called with the positional arguments args and keyword arguments keywords" > ... which made me initially think that in order to behave like the passed > in function: it should have __name__ and __qualname__... like the func did. > > 2: I would say have both __qualname__ and __name__. Both could be based > off of __name__/__qualname__ of the passed in func. > > 3: This would be more difficult since you would have to disassemble the > lambda to figure out the called method (or methods)... We can table the > lambda discussion for the purpose of this idea. I recall that typically it > is preferred to use partial over lambdas, so this could be an additional > functionality/benefit of using partial over lambda. > > Notes: > ... __name__ being something like partial(foo, "x") would be fine with > me... I just feel as though something should be there. > > - Charlie Scott Machalow > > > On Mon, Aug 29, 2022 at 9:56 PM Paul Bryan <pbr...@anode.ca> wrote: > >> +0 >> >> Questions: >> >> 1. What's the use case for partial having __name__? >> 2. Does this imply it should have __qualname__ as well? >> 3. What name would be given to (an inherently anonymous) lambda? >> >> Notes: >> >> 1. I would prefer __name__ to be more qualifying like its repr (e.g. >> partial(foo, "x") → "<partial foo>") >> >> >> On Mon, 2022-08-29 at 21:31 -0700, Charles Machalow wrote: >> >> Hey folks, >> >> I propose adding __name__ to functools.partial. >> >> >>> get_name = functools.partial(input, "name: ") >> >>> get_name() >> name: hi >> 'hi' >> >>> get_name.__name__ >> Traceback (most recent call last): >> File "<stdin>", line 1, in <module> >> AttributeError: 'functools.partial' object has no attribute '__name__' >> >>> get_name.func >> <built-in function input> >> >>> get_name.func.__name__ >> 'input' >> >> We could set __name__ based off of partial.func.__name__ or we could try >> to set it to something like 'partial calling func.__name__' >> >> If the callable doesn't have a name, we could fall back to a None >> __name__ or set it to something generic. >> >> Even lambdas have __name__ set: >> >> >>> l = lambda: input('name: ') >> >>> l.__name__ >> '<lambda>' >> >> This proposal makes __name__ on partial objects more useful than the >> current behavior of __name__ on lambda objects as well. We could port over >> similar functionality to lambda if we'd like. >> >> - Charlie Scott Machalow >> _______________________________________________ >> Python-ideas mailing list -- python-ideas@python.org >> To unsubscribe send an email to python-ideas-le...@python.org >> https://mail.python.org/mailman3/lists/python-ideas.python.org/ >> Message archived at >> https://mail.python.org/archives/list/python-ideas@python.org/message/WK3FO357ORPVAD3XRUBRH6IHIYSPS3G2/ >> Code of Conduct: http://python.org/psf/codeofconduct/ >> >> >> _______________________________________________ > Python-ideas mailing list -- python-ideas@python.org > To unsubscribe send an email to python-ideas-le...@python.org > https://mail.python.org/mailman3/lists/python-ideas.python.org/ > Message archived at > https://mail.python.org/archives/list/python-ideas@python.org/message/ONAEBCIEJ4DJNWUNWE2ESJ6SBB4O7O6W/ > Code of Conduct: http://python.org/psf/codeofconduct/ >
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