Objects Essentials

This session covers all the essentials of Python objects, from the most basic concepts to some advanced features, with real world examples and some exercises. The training contents are:

• Type, id and value
• Mutable vs. immutable types
• New-style vs. old-style classes
• Objects data model and customisation
• Inheritance: super, getattr and MRO
• Instantiation: new and init
• Metaclasses

Usage

All the course content is written down in Python scripts, designed to be executed with pydemo.

To execute yourself all the code:

• Create a virtualenv (optional):

me@my_laptop:~/workspace/objects (master)$ virtualenv ~/venvs/objects_essentials -p python2.7
Running virtualenv with interpreter /usr/bin/python2.7
New python executable in /Users/pev/venvs/objects_essentials/bin/python
Installing setuptools............done.
Installing pip...............done.
me@my_laptop:~/workspace/objects (master)$ source ~/venvs/objects_essentials/bin/activate

• Install readline with easy_install:

(objects_essentials)me@my_laptop:~/workspace/objects (master)$ easy_install readline
Searching for readline
...
Finished processing dependencies for readline

• Install the requirements.txt with pip:

(objects_essentials)me@my_laptop:~/workspace/objects (master)$ pip install -r wspace/objects/requirements.txt
Downloading/unpacking git+git://github.com/pablito56/pydemo.git (from -r wspace/objects/requirements.txt (line 3))
...
Successfully installed Pygments nose pydemo
Cleaning up...

• Execute pydemo console (use -h to check its arguments):

(objects_essentials)me@my_laptop:~/workspace/objects (master)$ pydemo
Loaded 4 files, 238 code blocks
Python 2.7.2 (default, Oct 11 2012, 20:14:37)
[GCC 4.2.1 Compatible Apple Clang 4.0 (tags/Apple/clang-418.0.60)] on darwin
Type "help", "copyright", "credits" or "license" for more information.
(DemoHistoryConsole)
>>>
#-*- coding: utf-8 -*-
###
# MODULE 01: Objects: type, id, value, mutable vs. immutable
###

>>>
# Let's instantiate a string and check its id, type and value
str_inst = 'abcd'
print id(str_inst)
print type(str_inst)
print str_inst

4524942560
<type 'str'>
abcd
>>> str_inst
'abcd'
>>>

Alternatively you can open the Python modules with you preferred Python editor and execute code blocks manually.