Hello,
On Thu, 14 Jan 2021 22:19:06 +1100
Steven D'Aprano <st...@pearwood.info> wrote:
> On Thu, Jan 14, 2021 at 02:05:50PM +0300, Paul Sokolovsky wrote:
>
> [...]
> > Semantically, Python can achieve the same with "imperative" syntax
> > like:
> >
> > def mixin_method(self, args):
> > ...
> > Cls.mixin_method = mixin_method
> >
> >
> > The question then: what are the best practices in *declarative*
> > syntax to achieve the same effect in Python? (but of course, unlike
> > Ruby, there should be explicit syntactic marker that we augment
> > existing class, not redefine it).
>
> def Cls.mixin_method(self, args):
> ...
>
> has been suggested as syntax for adding new methods to an existing
> class. I would use that occasionally.
Thanks for the info! But I'd say that I like syntax suggested by Chris
Angelico (which parallels Ruby's syntax) better. It reminds more of the
original class definition, and it's normal to add more than one
var/method via mixin/interface, so grouping them together using
"class ...:" makes sense. But "scoping" problems pops up nonetheless,
e.g. one would like, but really can't, do following:
import mod
@mixin
class mod.Cls:
...
So, here's the syntax I came to:
@mixin
class Cls(mod.Cls):
...
It literally reads like "let me add a mixin to class Cls
(specifically, mod.Cls)". IMHO, it's pretty neat. What do you think?
> Even more so, the generalisation:
>
> def obj.method(self, args):
> ...
>
> to add a method to any instance, not just to a class.
Nnnnooooo ;-). Instances can't have methods, only classes can.
Instances can only have instance variable storing a reference to a
method, which would need to be called (obj.method)(args), remember? ;-).
[]
--
Best regards,
Paul mailto:pmis...@gmail.com
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