Python Module Internal Representation and Introspection

Internal

• Python Introspection
• Python Language Modularization

The module Class

All module and package instances are represented internally as instances of the module class.

Checking whether an Object Instance is a Module

import types
import mymodule

assert isinstance(mymodule, types.ModuleType)
assert not isinstance('something', types.ModuleType)

Attributes

All object instances declared in the module (variables, functions, classes, etc.) become attributes of the module instance and they are accessible with inspect.getmembers().

inspect.getmembers()

Additionally, the following special attributes are present:

__name__

The __name__ special variable contains the name of the module, when it was imported, as string.

import mymodule
assert mymodule.__name__ == 'mymodule'

When the module is executed directly with python mymodule.py, it is never imported, so __name__ is set to the "__main__" string.

__file__

Once imported, the file associated with the module can be determined using the module object's __file__ attribute, as string:

import mymodule
[...]
print(mymodule.__file__)

The directory portion of __file__ should be one of the directories in sys.path.

__doc__

The content of the module docstring, if declared, otherwise None.

__package__

An empty string for a module, the name of the package for a package.

__path__

The __path__ attribute exists only for module instances that represent packages, not for those instances that represent ordinary modules.

__path__ contains a list with the paths of the package root directories, where the component modules, subpackages, __init__.py and __main__.py live.