modules_in_python

#As your program gets longer, you may want to split it into several files for easier maintenance. 
#You may also want to use a handy function that you’ve written in several programs without copying its definition into each program.
#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 

# Fibonacci numbers module
#  fibo.py 
def fib(n):    # write Fibonacci series up to n
    a, b = 0, 1
    while b < n:
        print b,
        a, b = b, a+b

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
    
#import this module with the following command:

import fibo  
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__

# 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

#There is a variant of the import statement that imports names from a module directly into the importing module’s symbol table. 
#For example:

>>> from fibo import fib, fib2
>>> fib(500)
1 1 2 3 5 8 13 21 34 55 89 144 233 377

# There is even a variant to import all names that a module defines:

>>> from fibo import *
>>> fib(500)
1 1 2 3 5 8 13 21 34 55 89 144 233 377