Python: Modules, Classes & Objects

README.md

Python: Modules, Classes & Objects

So in Python you have 3 major tools for code organization…Modules, Classes, & Objects

Modules:

Python modules are pretty much just a single python file. You can think about it as giving your variables and functions a specific namespace to reference within another python script. For example: The code below imports the contents of "mySampleModule.py" to allow all it's contents to be used in another python script under it's namespace (by default, the filename).

import mySampleModule

To then run a function from this module, you would then write something like this…

mySampleModule.sampleFunction()

or to access a variable within a module…

mySampleModule.sampleVariable

You can also import a module and assign an alias (alternate namespace) like this… allowing code be a bit less bloated. The sample below is the same as the last 3 examples together.

import mySampleModule as msm
msm.sampleFunction()
msm.sampleVariable

Classes & Objects:

A Class is a concept similar to a module, as it can also contain it's own variables and functions. The difference is it allows the user to create multiple instances of “objects”. Conceptually, you can think of this as similar to referencing multiple instances (objects) of a rig (class) within a scene: The rig is referenced from the same file, but you can alter and animate each one differently.

This is a decent reference/tutorial explaining their differences: http://learnpythonthehardway.org/book/ex40.html

example.py

class Person():
    def __init__(self):
        self.firstName = 'unknown'
        self.lastName = 'unknown'

    def setFirstName(self, name):
        self.firstName = name

    def setLastName(self, name):
        self.lastName = name

    def getFullName(self):
        return self.firstName + ' ' + self.lastName


fred = Person()                    #__init__ is run immediately
bob = Person()                     #__init__ is run immediately

bob.firstName                      # currently equals 'unknown'
bob.setFirstName('Fred')
bob.setLastName('Johnson')
bob.firstName                      # currently equals 'Fred'
print(bob.getFullName())           # 'Fred Johnson'

fred.firstName                     # currently equals 'unknown'
fred.setFirstName('Bob')
fred.setLastName('Malooga')
fred.lastName                      # currently equals 'Malooga'
print(fred.getFullName())           # 'Bob Malooga'
fred.setLastName('Maloogaloogaloogaloogalooga')
print(fred.getFullName())           # 'Bob Maloogaloogaloogaloogalooga'