CODEWITHSUNDEEP
pythonlinux
sowamy
sowamy

Reputation: 1

Where can I locate the library for python base functions in Linux?

I am mainly trying to get examples from the library of the base functions to help aid me in my studies of Python. I am running Linux Mint 17 and I would like to simply know the path to the base functions, so I can open them and view the Python code they contain.

Upvotes: 0

Views: 148

Answers (2)

Cld
Cld

Reputation: 481

Each non built-ins modules have a __file__ attribute. He contains the fullpath of the loaded file, so if it's a module write in python, you will get a '.pyc' file, if it's a C module a '.so'.

>>> import collections  # from the std lib in pure python
>>> collections.__file__
'/usr/lib/python2.7/collections.pyc'
>>> import datetime  # from the std lib as a C module
>>> datetime.__file__
'/usr/lib/python2.7/lib-dynload/datetime.so'
>>> import itertools  # from the std lib but a built-in module
>>> itertools.__file__
Traceback (most recent call last):
  File "<stdin>", line 1, in <module>
AttributeError: 'module' object has no attribute '__file__'

You can also use the inspect module, who have a .getsourcefile function, this work not only at module level but a function level too. If the function is declared in python !

>>> import inspect
>>> inspect.getsourcefile(collections)  # Pure python
'/usr/lib/python2.7/collections.py'
>>> inspect.getsourcefile(collections.namedtuple)  # Work with a function too.
'/usr/lib/python2.7/collections.py'
>>> inspect.getsourcefile(datetime)  # C module so it will return just None
>>> inspect.getsourcefile(itertools)  # Built-in so it raise an exception
Traceback (most recent call last):
  File "<stdin>", line 1, in <module>
  File "/usr/lib/python2.7/inspect.py", line 444, in getsourcefile
    filename = getfile(object)
  File "/usr/lib/python2.7/inspect.py", line 403, in getfile
    raise TypeError('{!r} is a built-in module'.format(object))
TypeError: <module 'itertools' (built-in)> is a built-in module

Has you can see, if it's a external C library, .getsourcefile return nothing. And if it's a built-in module/function/class, it raise a TypeError exception.

The others advantages of .getsourcefile over __file__ is that if the function/class is declared in a subfile of the module it return the right file. And you can even use it on the type of a "an unknown" object and do inspect.getsourcefile(type(obj)).

(It's test if the source file exist too and return None if the '.pyc' is loaded but the '.py' doesn't exist)

Upvotes: 2

ch3ka
ch3ka

Reputation: 12158

The base install is usually in /usr/lib{,64}/python*/, and installed packages in /usr/lib{,64}/python*/site-packages:

ch3ka@x200 /tmp % locate this.py | grep python3\.4
/usr/lib64/python3.4/this.py

(this is the path to the module this - substitute 3\.4 with your python version, or simply skip the | grep)

But when using virtualenv, your PYTHONPATH may be anywhere, depends on what you specified when creating the virtualenvs. Use locate(1) and your judgement.

Upvotes: 0

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