builtin_function_or_method is also either a function or a method #91370

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1. ravi140222 commented on Apr 4, 2022

   

   ravi140222mannequin

   on Apr 4, 2022

   MannequinAuthor

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   the.

   import inspect
   inspect.isfunction
   

   does not consider a

   builtin_function_or_method
   

   as a function.
   for example,

   inspect.isfunction(abs)
   

   gives,

   False
   

   in the background even the builtin abs is a function, so shouldn't it return True?

   the way this check is implemented is by matching the type of a builtin_function_or_method with,

   type(len)
   

   and since, type(len) is builtin_function_or_method, so, the inspect.isfunction check gives False.
   But in my opinion, it should return True, even for builtin functions or methods.
2. ravi140222

   added

   3.11only security fixesonly security fixes

   buildThe build process and cross-buildThe build process and cross-build

   on Apr 4, 2022
3. sweeneyde commented on Apr 4, 2022

   

   sweeneyde

   on Apr 4, 2022

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   https://docs.python.org/3/library/inspect.html#inspect.isfunction says this:

   """
   inspect.isfunction(object)
   Return True if the object is a Python function, which includes functions created by a lambda expression.
   """

   Emphasis on the "Python function", as in, something written in Python using a def statement or a lambda expression. If isfunction returns True, you can presumably access function-specific implementation details like the functions's f.code attribute. If you need to check for "anything that works as a function", you can use callable():

   >>> callable(lambda: 2)
   True
   >>> callable(abs)
   True
   >>> def f(x): return x
   >>> callable(f)
   True

   I'm not an expert on the inspect module, but I'm guessing it's not worth breaking backwards-compatibility to change this behavior.

   Would extra emphasis in the documentation have been helpful for you, or were you mostly attempting to rely on the function's name?
4. ravi140222 commented on Apr 4, 2022

   

   ravi140222mannequin

   on Apr 4, 2022

   MannequinAuthor

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   but callable returns True for classes with __call__ also, it does not check whether the argument passed to it is a function or not.

   I want some way to return True for both builtin functions and Python functions, but not for classes.

   And similarly, some way to return True for both builtin methods and Python methods.

   Should the documentation for inspect.isfunction include, this does not include builtin functions., and similarly for inspect.ismethod?

   Should I create a PR to add these two sentences to the documentation?
5. stevendaprano commented on Apr 4, 2022

   

   stevendaprano

   on Apr 4, 2022

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   Perhaps what you want is inspect.isroutine ?

   https://docs.python.org/3/library/inspect.html#inspect.isroutine

   I agree with Dennis that the isfunction test is for **Python** (def or lambda) functions, not builtins. The docstring for the inspect.is* methods make promises about what attributes an object will have:

   def isbuiltin(object):
       """Return true if the object is a built-in function or method.
       Built-in functions and methods provide these attributes:
           __doc__         documentation string
           __name__        original name of this function or method
           __self__        instance to which a method is bound, or None"""
   
   
   def isfunction(object):
       """Return true if the object is a user-defined function.
       Function objects provide these attributes:
           __doc__         documentation string
           __name__        name with which this function was defined
           __code__        code object containing compiled function bytecode
           __defaults__    tuple of any default values for arguments
           __globals__     global namespace in which this function was defined
           __annotations__ dict of parameter annotations
           __kwdefaults__  dict of keyword only parameters with defaults"""

   def (and lambda) functions have a different API from builtin_function_or_method objects. They should be kept separate.
6. ravi140222 commented on Apr 4, 2022

   

   ravi140222mannequin

   on Apr 4, 2022

   MannequinAuthor

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   yes, I think inspect.isroutine does the required functionality.
   sorry, I did not know about it, and could not think of the word routine when checking for functions.
7. ezio-melotti

   transferred this issue fromon Apr 10, 2022
8. carlbordum commented on May 10, 2022

   

   carlbordum

   on May 10, 2022

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   I believe this issue can be closed.
9. iritkatriel

   closed this as completedon May 10, 2022