Modular Programming

Modular Programming is coding method that separates the program into independent, interchangeable parts

• helps handle very large programs
• helps with debugging and testing
• makes code more readable

Structure of a Program

A Python program is constructed from code blocks

A block is a piece of Python program text that is executed as a unit

The following are blocks:

• a module
• a function body
• a class definition.
• others

Names and Binding

Names refer to objects

Names are introduced by name binding operations

The following constructs bind names:

• formal parameters to functions
• import statements
• class and function definitions (these bind the class or function name in the defining block)
• targets that are identifiers if occurring in an assignment
• for loop header, or after as in a with statement or except clause

The import System

The import System

Python code in one module gains access to the code in another module by the process of importing it

The import statement is the most common way of invoking the import machinery

import math

The import statement (with no from clause) is executed in 2 steps:

1. find a module, loading and initializing it if necessary
2. define a name or names in the local namespace for the scope where the import statement occurs.

• Failure at the first step may indicate that the module could not be located, or that an error occurred while initializing the module, which includes execution of the module’s code

When the statement contains multiple clauses (separated by commas) the two steps are carried out separately for each clause:

import math, os