Jython Essentials

Chapter 4. Modules and Functions

The three basic building blocks of a Python program are modules, functions, and classes. This chapter will discuss modules and functions, while the next chapter will discuss classes. A Python module is a collection of statements that define variables, functions, and classes, and that is the primary unit of a Python program for the purposes of importing code. Importing a Python module actually executes the module. A function in Python is similar to functions or methods in most programming languages. Python offers a rich and flexible set of mechanisms for passing values to functions.

Modules

Python helps you to organize your programs by using modules. You can split your code among several modules, and the modules can be further organized into packages. Modules are the structural units of Python programs. In Java, this structural role is played directly by classes, and there is a strict correspondence between a file’s name and the class it contains. In Python, the filename is used only for organization, and does not require specific names to be used for any object within that file.

A Python module corresponds to a source code file containing a series of top-level statements, which are most often definitions of functions and classes. These statements are executed in sequence when the module is loaded. A module is loaded either by being passed as the main script when the interpreter is invoked or when the module is first imported by another module. This ...