The ABCs of Python Modules: Simplifying Code Complexity

Python Modules

What Are Python Modules?

Python modules enable you to break your programs up into more manageable pieces that can be more easily accessed, used, and maintained - making it simpler to add new functionality or make modifications without breaking the whole program. Python modules also increase code reusability and efficiency.

As you start writing programs in Python, typically your function definitions will all go in one file. When your program grows larger you may wish to split its components up for easier maintenance and reuse of code; Python modules offer the perfect solution as they allow import functions or variables from another file.

Modules are files containing definitions for functions, classes, variables, constants and other Python objects that can be made accessible to any other program using import keyword. This allows you to keep your code organized while still giving you flexibility of using objects from various files.

Importing modules will populate your local symbol table with all of their names; any attempt at using one in your script which already exist as part of another module may lead to errors; in such instances it's wiser to either use def to define an original function with similar names, or import modules that contain such functions as possible solutions.

Python provides many pre-defined modules with useful built-in functions, such as print(), input(), list(), dict() etc. that make its distribution much more manageable and user friendly.

Packages are modules that can be installed using a package manager such as Pip and can then be imported into scripts just like any other module.

As part of Python's efficient execution time, modules are byte-compiled. This process converts source code into an intermediate form called bytecode that can then be translated to machine language by its interpreter and executed on your computer - this gives Python its fast runtime!

As soon as your modules become complex, however, this can become a bottleneck. Python's caching feature provides an effective solution - an compiled version of each module is stored in memory and may be reused if necessary.

Whenever a module is loaded, its __init__.py file is executed to initialize any necessary code that needs to be done by it. For instance, if its function definitions need compiling or loading for use from scripts then they will only do this once; subsequent calls use precompiled versions if available in memory and this eliminates having to compile and rerun every time there's an update made to it.

What is a Module?

A module is identical to an application library.

A file that includes a set of functions that you wish to incorporate into your application.

Create a Module

To make a module, save the code that you would like to create in a file that has the extension .py:

Example

Save this code to an archive file called mymodule.py 

def greeting(name):
  print("Hello, " + name)

Use a Module

We are now able to utilize the module that we created earlier, making use of this import statement:

Example

Import the module called mymodule. Then, call your greeting service:

import mymodule

mymodule.greeting("Jonathan")

Note: When using a function from a module, use the syntax: module_name.function_name.

Variables in Module

The module may contain functions, as mentioned, but it also contains variables of every type (arrays and dictionaries etc.):

Example

Copy this code into the directory mymodule.py

person1 = {
  "name": "John",
  "age": 36,
  "country": "Norway"
}

Example

Import the module mymodule. Then, access to the Person1 Dictionary:

import mymodule

a = mymodule.person1["age"]
print(a)

Naming a Module

The module can be named the file however you want however, it must include the extension of .py

Re-naming a Module

You can make an alias after an import of a module by using in keyword:

Example

Create an Alias that is a reference to mymodule named MX:

import mymodule as mx

a = mx.person1["age"]
print(a)

Built-in Modules

There are a variety of built-in modules available in Python that you are able to import at any time you'd like.

Example

Import and then use platform module: Import and use Platform module:

import platform

x = platform.system()
print(x)

Utilizing the dir() Function.

It has a built-in method to show all the names of functions (or variables names) within the module. It is called the function dir() function:

Example

Find all the known names that are part of this platform module:

import platform

x = dir(platform)
print(x)

Note: The dir() function can be utilized in any of the modules, not just those you design by yourself.

Import From Module

You may choose to import only the parts of an existing module, using in keyword.

Example

The module called mymodule is a single function with one dictionary:

def greeting(name):
  print("Hello, " + name)

person1 = {
  "name": "John",
  "age": 36,
  "country": "Norway"
}

Example

Only import Person1's dictionary directly from module:

from mymodule import person1

print (person1["age"])

Note: When you import using the from keyword, don't use the module's name when referring to the elements within the module. Example: person1["age"] , Not mymodule.person1["age"]