Why can't I use inspect.getsource() to view the source for list?

Question

I tried to retrieve the source code for the list class using the inspect module, without success:

>>> import inspect
>>> inspect.getsource(list)
Traceback (most recent call last):
File "<stdin>", line 1, in <module>
File "/usr/lib/python2.7/inspect.py", line 701, in getsource
    lines, lnum = getsourcelines(object)
File "/usr/lib/python2.7/inspect.py", line 690, in getsourcelines
    lines, lnum = findsource(object)
File "/usr/lib/python2.7/inspect.py", line 526, in findsource
    file = getfile(object)
File "/usr/lib/python2.7/inspect.py", line 408, in getfile
    raise TypeError('{!r} is a built-in class'.format(object))
TypeError: <module '__builtin__' (built-in)> is a built-in class

I don't understand why this didn't work - the documentation for inspect.getsource() says that

An IOError is raised if the source code cannot be retrieved.

... but doesn't explain why that might happen (and in any case I got a TypeError, not an IOError).

Is there some other way I can programmatically retrieve the source for an object in cases like this? If not, how can I find the source for myself?

Answer 1

While inspect.getsource() can retrieve the source code for objects written in Python, list is written in C, so there's no Python source for getsource() to retrieve.

If you're comfortable reading C, you can find the complete source code for Python at its official GitHub repo. For example, the source of list for various releases can be found at:

• https://github.com/python/cpython/blob/master/Objects/listobject.c (latest development version)
• https://github.com/python/cpython/blob/3.6/Objects/listobject.c
• https://github.com/python/cpython/blob/2.7/Objects/listobject.c

... and so on.