为什么有些内置的Python函数只有pass？

Question

I wanted to see how a math.py function was implemented, but when I opened the file in PyCharm I found that all the functions are empty and there is a simple pass . For example:

def ceil(x): # real signature unknown; restored from __doc__
    """
    ceil(x)

    Return the ceiling of x as a float.
    This is the smallest integral value >= x.
    """
    pass

I guess it is because the functions being used are actually from the C standard library. How does it work?

Answer 1

PyCharm is lying to you. The source code you're looking at is a fake that PyCharm has created. PyCharm knows what functions should be there, and it can guess at their signatures using the function docstrings, but it has no idea what the function bodies should look like.

If you want to see the real source code, you can look at it in the official Github repository in Modules/mathmodule.c . A lot of the functions in there are macro-generated thin wrappers around C functions from math.h , but there's also a bunch of manually-written code to handle things like inconsistent or insufficient standard library implementations, functions with no math.h equivalent, and customization hooks like __ceil__ .

Answer 2

There are no source code written in python for some python libraries. These libraries was written on C or another languages. They are not presented by .py files and PyCharm or any another IDE cannot open their sources in readable view.

You can check sources in ...\AppData\Local\Programs\Python\Python310\Lib\site-packages . Most likely in your-package folder there will be .pui, .pud, .dll and other similiar files