Stephan Houben wrote:
Op 2017-10-01, Bill schreef <bill_nos...@whoknows.net>:
I watched an example on YouTube where someone wrote a simple descriptor
("@Time_it) to output the amount of time that it took ordinary functions
to complete. To be honest, I AM interested in descriptors.
Are you sure you are not confusing deSCRIPTtors and deCORAtors here?
Yet, you are absolutely correct! Thank you for clarifying! From your
description, I can see that it was *decorators*, which drew my
interest. It appears that *property* is perhaps both a decorator and a
descriptor, at least when used as in the examples we have been
discussing. According to the language grammar, which all newbys like me
should have handy (remember my ADT acronym from another thread?),
decorators can be applied to a classdef, a funcdef, or a async_funcdef
(the latter I assume is a "callback" function definition). Surely the
difference in syntax between funcdef and async_funcdef will be revealed
to me by looking closer at the grammar! : )
Bill
@Time_it
is decorator syntax.
Despite the similarity in the words, there are totally different things.
Descriptors are objects with __get__, and optionally __set__ and
__delete__ methods (i.e. they implement the descriptor protocols).
Decorators aren't really an official type, but loosely speaking these
are any functions which can be applied meaningfully with a single
function or class as argument. Some very mundane functions can be
(ab)used as decorators.
In [1]: @repr
...: def hello():
...: pass
...:
In [2]: hello
Out[2]: '<function hello at 0x1048a50d0>'
Stephan
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