[Python-ideas] Assignment decorators (Re: The Descriptor Protocol...)
larry at hastings.org
Tue Mar 8 02:24:49 CET 2011
On 03/07/2011 08:08 PM, Chris Kaynor wrote:
> You seemed to have missed the example of:
> lhs = @dec1 123
> which would produce
> dec1(classobject, 'lhs', 123)
No, that was deliberately not part of my proposal. My thinking: most of
the time, this will be used in class scope for creating objects that
have their own reasonable default values. Why force people to type in a
default value that 99% of the time you don't care about? Allowing you
to override this default value would be done by making the decorator
callable and return a callable, like
lhs = @dec1(123)
Also, I thought the "@dec1 123" style just looked too weird. I admit it
isn't that much weirder than what I already proposed.
However, if there are great uses for assignment decorators outside class
scope, perhaps we need this original rhs. Other folks have pointed
out--what does something like this mean?
c = Class()
c.member = @dec
Does dec get 'c.member'? Is this useful for anything? Shall we narrow
the use of assignment decorators to just class scope?
On 03/07/2011 08:08 PM, Joao S. O. Bueno wrote:
> What you are calling "classobject" simply don't exist at this stage
> wen creating a new class.
Toldja it probably wasn't a good idea!
> This is Python, where function calls has "(" .
I'm not sure if this is part of a default signature or a rejoinder to
me. If the latter, let me point out that class/function decorators are
already function calls without parentheses; it seems natural enough that
assignment decorators would similarly lack them.
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