closure python

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# Closure in Python. Criteria include 
# 1. must have a nested function
# 2. nested function must refer to a value defined in the enclosing outer function
# 3. enclosing function must return a reference of nested function
# consequence: the variable in the enclosing scope is remembered even when the 
# variable goes out of scope or the function itself is removed from the current namespace.

# Illustration
def counter():
    count = 0
    def increment():
        nonlocal count
        count += 1
        return count
    return increment        # return reference to inner function

instance = counter()    # counter() function is out of namespace after this line
print(instance())       # but counter() function's inner function still works
print(instance())		# and count variable doesn't get refreshed to 0
print(instance())
# 1
# 2
# 3

# Pros: Closures can avoid the use of global values and provides some form of data hiding.
# When there is one method to be implemented in a class, closures can provide an 
# alternate and more elegant solution.
def make_multiplier_of(n):
    def multiplier(x):
        return x * n
    return multiplier

times3 = make_multiplier_of(3)  # Multiplier of 3
times5 = make_multiplier_of(5)  # Multiplier of 5

print(times3(9))
# Output: 27

print(times5(3))
# Output: 15

print(times5(times3(2)))
# Output: 30

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Source: Grepper

Tags: data-hiding function python return

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Contributed on Aug 14 2022

Grotesque Gibbon

0 Answers Avg Quality 2/10

python closure

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2

def init():
    '''

    :return: increment_num function
    '''
    num = 0

    def increment_num():
        '''
        increments a number by one each call
        :return: num + 1
        '''
        nonlocal num
        num += 1
        return num

    return increment_num


increment = init()

print(increment())
print(increment())

#  output 1 2

Popularity 9/10 Helpfulness 5/10 Language python

Source: codefreelance.net

Tags: python py

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Contributed on Aug 26 2022

Jerome Scott

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closures in python

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def make_counter():

    count = 0
    def inner():

        nonlocal count
        count += 1
        return count

    return inner

Popularity 9/10 Helpfulness 2/10 Language python

Source: zetcode.com

Tags: closures closure

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Contributed on Jun 09 2021

King Generous

0 Answers Avg Quality 2/10

closures in python

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0

def make_summer():

    data = []

    def summer(val):

        data.append(val)
        _sum = sum(data)

        return _sum

    return summer

Popularity 9/10 Helpfulness 1/10 Language python

Source: zetcode.com

Tags: closures closure

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Contributed on Jun 09 2021

King Generous

0 Answers Avg Quality 2/10

closure python

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# Closure in Python. Criteria include 
# 1. must have a nested function
# 2. nested function must refer to a value defined in the enclosing outer function
# 3. enclosing function must return a reference of nested function
# consequence: inner function that remembers the variables in its enclosing scope
# even when the outer function is done executing, the variable goes out of scope
# or the function itself is removed from the current namespace. 

# Illustration
def counter():
    count = 0
    def increment():
        nonlocal count
        count += 1
        return count
    return increment        # return reference to inner function

instance = counter()    # counter() function is removed from namespace after this line
print(instance())       # but counter() function's inner function still works
print(instance())       # and it remembers count variable, i.e. it does not get refreshed to 0
print(instance())
# 1
# 2
# 3

# Pros: Closures can avoid the use of global values and provides some form of data hiding.
# When there is one method to be implemented in a class, closures can provide an 
# alternate and more elegant solution.
def make_multiplier_of(n):
    def multiplier(x):
        return x * n
    return multiplier

times3 = make_multiplier_of(3)  # Multiplier of 3
times5 = make_multiplier_of(5)  # Multiplier of 5

print(times3(9))
# Output: 27

print(times5(3))
# Output: 15

print(times5(times3(2)))
# Output: 30

# Python decorators use closure extensively, as it takes a function as parameter
# adds functionality to it and returns the original function.

Popularity 8/10 Helpfulness 1/10 Language python

Source: Grepper

Tags: python

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Contributed on Aug 14 2022

Grotesque Gibbon

0 Answers Avg Quality 2/10

closure in python

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1

def outer_func(msg):
    mesg = msg
    
    def inner_func():
        print(mesg)
    return inner_func

hi_func = outer_func('Hi')
print(my_func.__name__)
hi_func()

hello_func = outer_func('Hello')
print(my_func.__name__)
hello_func()

Popularity 6/10 Helpfulness 1/10 Language python

Source: Grepper

Tags: python

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Contributed on Dec 20 2022

Akshit Singhal

0 Answers Avg Quality 2/10

python closure

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10

### Closure: Attaching nonlocal variables to nested functions
### When there is a nested function where inner function is dependent on
### nonlocal variable of outer function, closure helps to contain the variable
### of that outer function inside a tuple to supply it later to
### the inner function when needed

def foo():
    a = 5
    def bar():
        print(a)
    return bar

func = foo()
func() # 5

# What is closure : A tuple that contains nonlocal variables
type(func.__closure__)
# See the number of nonlocal variables
len(func.__closure__)
# See values of closures
func.__closure__[0].cell_contents

Popularity 3/10 Helpfulness 1/10 Language python

Source: Grepper

Tags: python

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Contributed on Dec 07 2023

Innocent Iguana

0 Answers Avg Quality 2/10

closure python

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