Python Module Name Example

programA.py

# The technical term for a text file of Python code (what we've been creating all semester) is a module.
#
# This file you're looking at right now, programA.py, is a module.
#
# The file name acts as the module name.
# I.e. for this file programA.py, the corresponding module name is `programA`.
#
# That's why if we wanted to import this file into another file, we'd just say `import programA`, not `import programA.py`
#
# Ok, now that we know what a module is, let's look towards what __name__ is...
# 
# Within a module, that module's name is avilable as a built-in Python variable called `__name__`
#
# If you run a module directly, the module name (__name__) is set to __main__.
#
# If you import a module into another module, the module name (__name__) is the file name.
#
# To see this in action, run programA.py and note the output.
# Then run programB.py (which imports programA) and note the output.
#

print "module name: " + __name__

# If this module is being run directly...
if __name__ == '__main__':

    print 'This program, programA, is being run by itself.'

# If this module is being imported...
else:

    print 'programA is being imported from another file.'




# Purpose:
# Encapsulating the code you want to execute inside a `if __name__ == '__main__':` statement is not necessary.
# However, it can be useful if you only want certain code to run when that file is being run directly,
# versus when it's being imported to another file.
#
# The best example of this is with our picture.py module--
# In that file there are numerous tests we only want to run when that file is run directly, 
# But we don't want those same tests to run when we're importing picture.py into another file.

# To accomplish this, the tests are nested in an `if __name__ == '__main__':`


# Ref: https://docs.python.org/2/tutorial/modules.html

programB.py

import programA

# Expected output when you run this file:
#   module name: programA
#   I am being imported from another file