decorators: Extend the Behaviour of a Function without Explicitly Modifying
A decorator is a function that receives a function, extends its
behaviour, and returned the altered function. Any caller that uses the
decorated function uses the same interface as it were the original,
undecorated function. Decorators serve two primary uses: (1) Enhancing the
response of a function as it sends data to a second component; (2)
Supporting multiple optional behaviours. An example of the first use is a
timer decorator that runs a function, outputs its execution time on the
console, and returns the original function's result. An example of the
second use is input type validation decorator that during running time
tests whether the caller has passed input arguments of a particular class.
Decorators can reduce execution time, say by memoization, or reduce bugs
by adding defensive programming routines.
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