decorators tutorials

[Bruno Desthuilliers]

james_027 a écrit :
> hi bruno,
> 
> That seems to be hard to read at all, or I am just very new to python?

or just new to higher order functions ? (ie: functions working on 
functions).

> With that decorator how do I take advantage of it compare when I just
> write a function that could do the same as what the decorator did? I
> could translate the could from above into ...
> 
> def check_login(msg):
>    #...
> def my_func(toto, tata):
>    #...
> 
> #call it like this
> check_login('msg')
> my_func('toto', 'tata')

The first (and already very important difference) is that, with your 
solution, you have to remember to explicitely call check_login before 
calling my_func, while the decorator will take care of this. This allow 
to factor out orthogonal behaviours (like permission management, logging 
etc). Now there are almost endless other possible uses - anything that 
requires adding metadata to functions (CherryPy's way of flagging 
request handlers), registering functions for later use (ie: entry points 
for a plugin system, rule-based dispatch etc), triggering other 
behaviours before and/or after the function call - possibly bypassing 
the call to the original function, etc, etc, etc.

Note that the important part here is not the @decorator syntax - which 
is just (nice) syntactic sugar - but the ability to use higher order 
functions.