Learning Python - Mark Lutz [3]
Enclosing Scope Loop Variables
Chapter Summary
Test Your Knowledge: Quiz
Test Your Knowledge: Answers
Test Your Knowledge: Part IV Exercises
V. Modules
21. Modules: The Big Picture
Why Use Modules?
Python Program Architecture
How to Structure a Program
Imports and Attributes
Standard Library Modules
How Imports Work
1. Find It
2. Compile It (Maybe)
3. Run It
The Module Search Path
Configuring the Search Path
Search Path Variations
The sys.path List
Module File Selection
Advanced Module Selection Concepts
Chapter Summary
Test Your Knowledge: Quiz
Test Your Knowledge: Answers
22. Module Coding Basics
Module Creation
Module Usage
The import Statement
The from Statement
The from * Statement
Imports Happen Only Once
import and from Are Assignments
Cross-File Name Changes
import and from Equivalence
Potential Pitfalls of the from Statement
Module Namespaces
Files Generate Namespaces
Attribute Name Qualification
Imports Versus Scopes
Namespace Nesting
Reloading Modules
reload Basics
reload Example
Chapter Summary
Test Your Knowledge: Quiz
Test Your Knowledge: Answers
23. Module Packages
Package Import Basics
Packages and Search Path Settings
Package __init__.py Files
Package Import Example
from Versus import with Packages
Why Use Package Imports?
A Tale of Three Systems
Package Relative Imports
Changes in Python 3.0
Relative Import Basics
Why Relative Imports?
The Scope of Relative Imports
Module Lookup Rules Summary
Relative Imports in Action
Chapter Summary
Test Your Knowledge: Quiz
Test Your Knowledge: Answers
24. Advanced Module Topics
Data Hiding in Modules
Minimizing from * Damage: _X and __all__
Enabling Future Language Features
Mixed Usage Modes: __name__ and __main__
Unit Tests with __name__
Using Command-Line Arguments with __name__
Changing the Module Search Path
The as Extension for import and from
Modules Are Objects: Metaprograms
Importing Modules by Name String
Transitive Module Reloads
Module Design Concepts
Module Gotchas
Statement Order Matters in Top-Level Code
from Copies Names but Doesn’t Link
from * Can Obscure the Meaning of Variables
reload May Not Impact from Imports
reload, from, and Interactive Testing
Recursive from Imports May Not Work
Chapter Summary
Test Your Knowledge: Quiz
Test Your Knowledge: Answers
Test Your Knowledge: Part V Exercises
VI. Classes and OOP
25. OOP: The Big Picture
Why Use Classes?
OOP from 30,000 Feet
Attribute Inheritance Search
Classes and Instances
Class Method Calls
Coding Class Trees
OOP Is About Code Reuse
Chapter Summary
Test Your Knowledge: Quiz
Test Your Knowledge: Answers
26. Class Coding Basics
Classes Generate Multiple Instance Objects
Class Objects Provide Default Behavior
Instance Objects Are Concrete Items
A First Example
Classes Are Customized by Inheritance
A Second Example
Classes Are Attributes in Modules
Classes Can Intercept Python Operators
A Third Example
Why Use Operator Overloading?
The World’s Simplest Python Class
Classes Versus Dictionaries
Chapter Summary
Test Your Knowledge: Quiz
Test Your Knowledge: Answers
27. A More Realistic Example
Step 1: Making Instances
Coding Constructors
Testing As You Go
Using Code Two Ways
Step 2: Adding Behavior Methods
Coding Methods
Step 3: Operator Overloading
Providing Print Displays
Step 4: Customizing Behavior by Subclassing
Coding Subclasses
Augmenting Methods: The Bad Way
Augmenting Methods: The Good Way
Polymorphism in Action
Inherit, Customize, and Extend
OOP: The Big Idea
Step 5: Customizing Constructors, Too
OOP Is Simpler Than You May Think
Other Ways to Combine Classes
Step 6: Using Introspection Tools
Special Class Attributes
A Generic Display Tool
Instance Versus Class Attributes
Name Considerations in Tool Classes
Our Classes’ Final Form
Step 7 (Final): Storing Objects in a Database
Pickles and Shelves
Storing Objects on a Shelve Database
Exploring Shelves Interactively
Updating Objects on