Question

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Understanding Python decorators

Could you please give a short code example that explains decorators?

Answer 1

A decorator takes the function definition and creates a new function that executes this
function and transforms the result.

@deco
def do():
    ...

is equivalent to:

do = deco(do)

Example:

def deco(func):
    def inner(letter):
        return func(letter).upper()  #upper
    return inner  # return a function object

#This
@deco
def do(number):
    return chr(number)  # number to letter
#end

# is equivalent to this
def do2(number):
    return chr(number)

do2 = deco(do2)
#end


# 65 <=> 'a'
print(do(65))
print(do2(65))
>>> B
>>> B

To understand the decorator, it is important to notice, that decorator created a new function do which is inner that executes func and transforms the result.