[Zope3-dev] Re: reasonable syntax for multi-adaptation

[Dominik Huber]

Brandon Craig Rhodes wrote:
> Tres Seaver <tseaver at palladion.com> writes:
> 
>> Martijn Faassen wrote:
>>
>>> IFoo.adapt() for normal adaptation
>>> IFoo.multiadapt() for multi adaptation
>> I'd rather have 'adapt' take *args for the contexts, and keywords
>> for extras (like name).
> 
> And you could make the "default=" another possible extra!  In which
> case our proposals at the moment compare something like this:
> 
>  Brandon
>       Utility?              IFoo()
>       Single adaptation     IFoo(a)
>       ... with default      IFoo(a, default=y)
>       Multi adaptation      IFoo(multi=(a,b))
>       ... with default      IFoo(multi=(a,b), default=y)
>       Named multi adapter   IFoo(multi=(a,b), name='z')
>       ... with default      IFoo(multi=(a,b), name='z', default=y)

This syntax is pretty comfortable because you get code completion for 
free if you are using an ide (ex. eclipse pydev).

At the moment IFoo() invokes the factory of an object (if registered). 
IMO the current implementation is a miss-feature because you can't 
assign any parameters. I would prefer that IFoo() does look up the 
default utility and IFoo(name='z') the named one.

But this change could break existing code.
> 
>  Martijn/Tres
>       Utility               IFoo.adapt()
>       Single adaptation     IFoo.adapt(a)
>       ... with default      IFoo.adapt(a, default=y)
>       Multi adaptation      IFoo.adapt(a,b)
>       ... with default      IFoo.adapt(a,b, default=y)
>       Named multi adapter   IFoo.adapt(a,b, name='z')
>       ... with default      IFoo.adapt(a,b, name='z', default=y)
> 
> Well, I have to admit, yours are a lot prettier.  The word "adapt"
> takes no more characters than my "multi", and parenthesis disappear!
> And though I might quibble that "adapt()" would be better spelled
> "utility()", there is a nice symmetry about your idea.
> 
>  - Both patterns make it explicit to anyone reading the code when a
>    default value is being passed, which should vastly reduce surprise.
+1

>  - Mine feels more natural and Pythonic to people who, like PvW in his
>    book, think of adaptation as being like casting.
+1



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Dominik Huber

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