Python Module Attributes: name, doc, file, dict
Python module has its attributes that describes it. Attributes perform some tasks or contain some information about the module. Some of the important attributes are explained below:
__name__ Attribute
The __name__ attribute returns the name of the module. By default, the name of the file (excluding the extension .py) is the value of __name__attribute.
>>> import math
>>> math.__name__
'math'
In the same way, it gives the name of your custom module.
>>> hello.__name__
'hello'
However, this can be modified by assigning different strings to this attribute. Change hello.py as shown below.
def SayHello(name):
print ("Hi {}! How are you?".format(name))
__name__="SayHello"
And check the __name__ attribute now.
>>> import hello
>>> hello.__name__
'SayHello'
The value of the __name__ attribute is __main__ on the Python interactive shell.
>>> __name__
'__main__'
When we run any Python script (i.e. a module), its __name__ attribute is also set to __main__.
For example, create the following welcome.py in IDLE.
print("__name__ = ", __name__)
Run the above welcome.py in IDLE by pressing F5. You will see the following result.
>>> __name__ = __main__
However, when this module is imported, its __name__ is set to its filename.
Now, import the welcome module in the new file test.py with the following content.
import welcome
print("__name__ = ", __name__)
Now run the test.py in IDLE by pressing F5. The __name__ attribute is now "welcome".
__name__ = welcome
This attribute allows a Python script to be used as an executable or as a module.
Visit __main__ in Python for more information.
__doc__ Attribute
The __doc__ attribute denotes the documentation string (docstring) line written in a module code.
>>> import math
>>> math.__doc__
'This module is always available. It provides access to the mathematical functions defined by the C standard.'
Consider the the following script is saved as test.py module.
"""This is docstring of test module"""
def SayHello(name):
print ("Hi {}! How are you?".format(name))
return
The __doc__ attribute will return a string defined at the beginning of the module code.
>>> import test
>>> test.__doc__
'This is docstring of test module'
__file__ Attribute
__file__ is an optional attribute which holds the name and path of the module file from which it is loaded.
>>> import io
>>> io.__file__
'C:\\python37\\lib\\io.py'
__dict__ Attribute
The __dict__ attribute will return a dictionary object of module attributes, functions and other definitions and their respective values.
>>> import math
>>> math.__dict__
{'__name__': 'math', '__doc__': 'This module is always available. It provides a
ccess to the\nmathematical functions defined by the C standard.', '__package__':
'', '__loader__': <class '_frozen_importlib.BuiltinImporter'>, '__spec__': Modu
leSpec(name='math', loader=<class '_frozen_importlib.BuiltinImporter'>, origin='
built-in'), 'acos': <built-in function acos>, 'acosh': <built-in function acosh>
, 'asin': <built-in function asin>, 'asinh': <built-in function asinh>, 'atan':
<built-in function atan>, 'atan2': <built-in function atan2>, 'atanh': <built-in
function atanh>, 'ceil': <built-in function ceil>, 'copysign': <built-in functi
on copysign>, 'cos': <built-in function cos>, 'cosh': <built-in function cosh>,
'degrees': <built-in function degrees>, 'erf': <built-in function erf>, 'erfc':
<built-in function erfc>, 'exp': <built-in function exp>, 'expm1': <built-in fun
ction expm1>, 'fabs': <built-in function fabs>, 'factorial': <built-in function
factorial>, 'floor': <built-in function floor>, 'fmod': <built-in function fmod>
, 'frexp': <built-in function frexp>, 'fsum': <built-in function fsum>, 'gamma':
<built-in function gamma>, 'gcd': <built-in function gcd>, 'hypot': <built-in f
unction hypot>, 'isclose': <built-in function isclose>, 'isfinite': <built-in fu
nction isfinite>, 'isinf': <built-in function isinf>, 'isnan': <built-in functio
n isnan>, 'ldexp': <built-in function ldexp>, 'lgamma': <built-in function lgamm
a>, 'log': <built-in function log>, 'log1p': <built-in function log1p>, 'log10':
<built-in function log10>, 'log2': <built-in function log2>, 'modf': <built-in
function modf>, 'pow': <built-in function pow>, 'radians': <built-in function ra
dians>, 'remainder': <built-in function remainder>, 'sin': <built-in function si
n>, 'sinh': <built-in function sinh>, 'sqrt': <built-in function sqrt>, 'tan': <
built-in function tan>, 'tanh': <built-in function tanh>, 'trunc': <built-in fun
ction trunc>, 'pi': 3.141592653589793, 'e': 2.718281828459045, 'tau': 6.28318530
7179586, 'inf': inf, 'nan': nan}
dir() is a built-in function that also returns the list of all attributes and functions in a module.
Learn more about module attributes in Python Docs.