Decorators:

Decorators can be hought of as functions which modify the functionality of another function. They help to make your code shorter and more 'pythonic'.



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def func():
    return 1



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func()









    Out[5]:





1



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s = 'this is a global variable'

def func():
    print locals()



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print globals()['s']









    



this is a global variable



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func()

{}



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def hello(name = 'rustom'):
    return 'Hello ' + name



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hello()









    Out[10]:





'Hello rustom'



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greet = hello



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greet









    Out[12]:





<function __main__.hello>



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greet()









    Out[13]:





'Hello rustom'



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# del hello



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greet









    Out[15]:





<function __main__.hello>



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greet()









    Out[16]:





'Hello rustom'



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hello()









    Out[17]:





'Hello rustom'



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greet2 = hello()



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greet2









    Out[19]:





'Hello rustom'



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greet2()









    



---------------------------------------------------------------------------
TypeError                                 Traceback (most recent call last)
<ipython-input-20-b4134b9ba083> in <module>()
----> 1 greet2()

TypeError: 'str' object is not callable



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del hello



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greet2









    Out[22]:





'Hello rustom'



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greet









    Out[23]:





<function __main__.hello>



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greet()









    Out[24]:





'Hello rustom'

function within function



In [25]:

    
def welcome(name = 'Prithvi'):
    print 'inside welcome()'
    
    def namaste():
        return '\t inside the namaste()'
    
    def hariom():
        return '\t inside hariom()'
    
    
    if name == 'Prithvi':
        return namaste
    else:
        return hariom



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x = welcome('potter')









    



inside welcome()



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print x()









    



	 inside hariom()

Passing functions as arguments



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def hello():
    return 'Namaste Prithvi!!'



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def other(func):
    print 'other code goes here'
    print func()



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other(hello)









    



other code goes here
Namaste Prithvi!!



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def new_decorator(func):
    def wrap_func():
        print 'code here....before executing the func'
        func()
        print 'code here....after executing the func'
    
    return wrap_func



In [32]:

    
def func_needs_decorator():
    print 'This function needs a decorator!!'



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func_needs_decorator()









    



This function needs a decorator!!



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m_func_needs_decorator = new_decorator(func_needs_decorator)



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m_func_needs_decorator









    Out[35]:





<function __main__.wrap_func>



In [36]:

    
m_func_needs_decorator()









    



code here....before executing the func
This function needs a decorator!!
code here....after executing the func



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@new_decorator
def another_funcNeedsDecorator():
    print 'Another function needing decorator'



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another_funcNeedsDecorator









    Out[38]:





<function __main__.wrap_func>



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another_funcNeedsDecorator()









    



code here....before executing the func
Another function needing decorator
code here....after executing the func



In [44]:

    
repr(x)









    Out[44]:





'<function hariom at 0x7f9f182c96e0>'



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str(x)









    Out[45]:





'<function hariom at 0x7f9f182c96e0>'



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