I've been learning how to use decorators in Python. As far I understand
it a decorator takes as input a function, does something with or to the
function and then returns the function. To test out this functionality
I've written five examples. First the following preamble is included at
the top of the file containing the decorator functions:
countit - will print a line to the terminal every time the function
is called with the number of times it has been called.
timeit - times how long a function takes to run and prints this to
logit - prints to the the terminal the output that is returned from
beforeit - runs a function that is passed as an argument to the
decorator before each function call.
afterit - runs a function that is passed as an argument to the
decorator after each function call.
Each of these decorators can be used individually or as a group. For
example, this is a function that computes prime numbers in a rather
inefficient manner by calculating the factors of each number smaller
than it (a better method would be to use the seive of
It has been decorated with the first three functions above. It is then
called three times as follows:
The output produced is:
So whenever I am writing a new python programme I can now import my
decorators file and I will have access to the timeit, countit and logit
beforit and afterit decorators to aid in debugging.
If you can think of any other useful applications for decorators please
let me know in the comments.