Course on python at the CLTL (OOP)

1. CLTL Python Course
Object Oriented Programming in Python
2nd session
May 1st 2013

2. Reminder session 1
● What is Object Oriented Programming
● Classes, objects, methods, properties...
● How to define classes, with methods and attributes
● How to create objects
● The __init__ method
● Basic inheritance

3. Session 2
● How organize and reuse our code
– Scripts
– Classes
– Modules
– Packages
● How to use eclipse with python
– Creating projects, modules
– Example

4. Python modules
● A module is a file containing python definition and
statements
● The name of the module is the name of the file without .py
– File: fibo.py Name module: fibo
● The module name is important --> to reuse the module
– Import statement
● Inside the module the name is stored in the variable
__name__
● A script is a module which defines a MAIN function:
– When you run a module (python fibo.py) --> the mod.
Name is set to __main__
if __name__ == '__main__':

5. Importing modules
● Module “ruben” (file ruben.py)
– 3 functions: say_hello(), add(a,b), say_bye()
● We want to reuse this module in other modules
– import ruben
● Imports everything in the module
● Access: ruben.say_hello() ruben.add(2,3)
– from ruben import *
● Imports everything in the module
● Access: say_hello() say_bye()
– from ruben import add
● Imports only what you specify (add)
● Access: add(4,5)

6. More on modules
● Function dir(module) --> gives you all the content of the mod
– Import ruben
– dir(ruben) --> [...,'say_hello', 'add', 'say_bye']
● Module search path: (where python looks when “import”)
1. Current directory
2. PYTHONPATH environment variable
3. Default location in your installation
● You can modify inside your script the variable sys.path (list)
to modify the PYTHONPATH
● Import sys
● Sys.path.append('C:/ruben/example/my_code)

7. Python Packages
● A way of structure and reuse modules
● Access through “dotted module names”
– modA.modB.modC --> submodule modC inside
submodule modB inside module modA
● At low level a python package is a folder with some
python modules and one file called __init__.py
– This __init__ is called when we import the
package to initialization

8. Example Python Package
● Package to handle different sound files and data

9. Example Python Package
● Package to handle different sound files and data
DIFFERENT WAYS OF IMPORTING / USING
Import sounds.effects.echo
--> sunfs.effects.echo.echofilter(....)
From sound.effects import echo
--> echo.echofilter(....)
From sound.effects.echo import echofilter
--> echofilter(...)
From sound.effects import *
--> depends on the __all__ defined in
sound.effects.__init__
__all__ = ['echo','surround']

10. Eclipse + PyDev