closure

1
Closure
2

• A function which returns another function as
  output.
• A closureunlike a plain functionallows the
  function to
• access those captured variables through the
  closures copies of
• their values or references, even when the
  function is invoked
• outside their scope.
• As closures are used as callback functions, they
  provide some
• sort of data hiding. This helps us to reduce the
  use of
• global variables.

3

• Egdef f1() print('This is f1 Function') def f
  2() print('This is f2 function') return f2a 
   f1()print(a) a()
• O/P This is f1 Function ltfunction
  f1.ltlocalsgt.f2 at 0x7fc192fc66a8gt This is f2
  function

4
Decorators in Python

• Decorators are function which takes one function
  as input and returns a modified function as output
  , used mainly to modify an existing function
• Decorators are very powerful and useful tool in
  Python since it allows programmers to modify the
  behaviour of function or class. Decorators allow
  us to wrap another function in order to extend
  the behaviour of wrapped function, without
  permanently modifying it.
• In Decorators, functions are taken as the
  argument into another function and then called
  inside the wrapper function.
• There are some decorators already defined in
  python such as _at_classmethod ,_at_staticmethod
  ,_at_property
• Syntax _at_abc_decoratordef hello_decorator()
  print(abc")

5

• Egdef decorator(func)  def wrapper(x,y)  if
   y  0 print('Number can not be divided by 0'
  ) else print(func(x,y))return wrapper_at_deco
  ratordef existing_func(a,b) return a//bexistin
  g_func(10,2)
• O/P 5

6
Generators in Python

• Generator-Function  A generator-function is
  defined like a normal function, but whenever it
  needs to generate a value, it does so with
  the yield keyword rather than return. If the body
  of a def contains yield, the function
  automatically becomes a generator function.
• Generator-Object  Generator functions return a
  generator object. Generator objects are used
  either by calling the next method on the
  generator object or using the generator object in
  a for in loop (as shown in the above program).

7

• Eg def my_gen()  yield 10   yield 20
  yield 20
•  for i in my_gen()  print(i)
• O/P10 20 20
• Eg2def my_gen()  num-5
• while(numlt3) yield num num1
• amy_gen()
• for i in a
•    print(i)
• O/P-2 -1 0 1 2 3

8
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