This chapter begins our in-depth look at the Python module, the highest-level program organization unit, which packages program code and data for reuse. In concrete terms, modules usually correspond to Python program files (or extensions coded in external languages such as C, Java, or C#). Each file is a module, and modules import other modules to use the names they define. Modules are processed with two statements and one important function:
Lets a client (importer) fetch a module as a whole
Allows clients to fetch particular names from a module
Provides a way to reload a module’s code without stopping Python
Chapter 3 introduced module fundamentals, and we’ve been using them ever since. This part of the book begins by expanding on core module concepts, then moves on to explore more advanced module usage. This first chapter offers a general look at the role of modules in overall program structure. In the following chapters, we’ll dig into the coding details behind the theory.
Along the way, we’ll flesh out module details omitted so far:
you’ll learn about reloads, the
__all__ attributes, package imports, relative
import syntax, and so on. Because modules and classes are really just
glorified namespaces, we’ll formalize namespace concepts here as
In short, modules provide an easy way to organize components into a system by serving as self-contained packages of variables known as namespaces. All ...