We, ‘pygrammers’
(python programmers) knew about the great python interpreter. We also know that whatever we
type into the interpreter vanishes as soon as we close the interpreter.
So if
you want to use some of the definitions and statements in other programs without rewriting the
definition, we use a special type of container called the ‘MODULE’.
The process
of creating definitions and saving it in a file is called “writing a script”.
A module is a
python file ( filename.py) which contains statements and some definitions.
Why Modules?
Imagine that
you want to build an application which consists of a million lines of code.
As an efficient programmer you must use the
concept of ‘re-use’ because unnecessarily writing the same code multiple times will not
only lead to increase in the length of the program but also effects the program's efficiency.
To support this, Python has a way to put definitions in a
file and use them in a script or in an interactive instance of the interpreter.
Such a file is called a module; definitions from a module can be imported into
other modules or into the main module.
For instance, let us write the following code using a text editor and saving with a file name with the extension '.py'
# Fibonacci numbers module
def fib(n): # write Fibonacci series up to n
a, b = 0, 1
while b < n:
print(b, end=' ')
a, b = b, a+b
print()
def fib2(n): # return Fibonacci series up to n
result = []
a, b = 0, 1
while b < n:
result.append(b)
a, b = b, a+b
return result
Now enter the
Python interpreter and import this module with the following command:
>>>
This does not enter
the names of the functions defined in fibo directly in
the current symbol table; it only enters the module name fibo there. Using
the module name you can access the functions:
>>>
>>> fibo.fib(1000)
1 1 2 3 5 8 13 21 34 55 89 144 233 377 610 987
>>> fibo.fib2(100)
[1, 1, 2, 3, 5, 8, 13, 21, 34, 55, 89]
>>> fibo.__name__
'fibo'
If you intend to
use a function often you can assign it to a local name:
>>>
>>> fib = fibo.fib
>>> fib(500)
1 1 2 3 5 8 13 21 34 55 89 144 233 377
The examples have been taken from the Official documentation.
