Koroskin Denis Wrote:
> 
> Yes, it's a good idea, but your solution introduces virtual function calls that could kill performance.

But most of D's methods are virtual.  Nobody minds that opEquals or toString are virtual and they're used a lot.  Yes, it will be a performance hit for the builtin implementation but would be the same for the programmer defined implementations.  If they're going to have to use a custom class anyway, why not allow them to have the syntax to go with it?

Often in languages and compilers, you have to choose between flexibility and speed, and that's a deicision for Walter.

> Much better approch would be the following:
> 
> - Provide an "interface" that built-in AAs implement.
> - Allow user-defined types to implement this interface.
> - Allow these derived types to benefit from all the syntax sugar, used by
> built-in containers.
> - Allow users to replace built-in containers with user-defined ones.
> (arguable)
> 
> Third point is necessary since there are still some tricks that can't be
> used by programmer like 'in' operator in AAs.
> This way containers could be replaced by user-defined types partially or
> completely.

Why couldn't a person use "in" on a user-defined AA?  According to the docs, its overloadable with opIn (but no example on the page so maybe its not supported anymore).

Kaja:
> Often in languages and compilers, you have to choose between flexibility and speed,

D AA are already plenty slow. So I'd try to find a way to have both speed and flexibility.


> Why couldn't a person use "in" on a user-defined AA?  According to the docs, its overloadable with opIn (but no example on the page so maybe its not supported anymore).<

You can use the opIn_r operator with no problems.

Bye,
bearophile

On 31/03/2008, Kaja <kaja.fumei@gmail.com> wrote:
> Why couldn't a person use "in" on a user-defined AA?  According to the docs, its overloadable with opIn (but no example on the page so maybe its not supported anymore).

It's completely usable. I've used it.

But of course, you'd use opIn_r(), not opIn(), because it's "element
in container", not "container in element".

On Mon, 31 Mar 2008 22:15:00 +0400, bearophile <bearophileHUGS@lycos.com> wrote:

> Kaja:
>> Often in languages and compilers, you have to choose between flexibility and speed,
>
> D AA are already plenty slow. So I'd try to find a way to have both speed and flexibility.
>
>
>> Why couldn't a person use "in" on a user-defined AA?  According to the docs, its overloadable with opIn (but no example on the page so maybe its not supported anymore).<
>
> You can use the opIn_r operator with no problems.
>
> Bye,
> bearophile


My bad, didn't know it's already supported. :)

> D AA are already plenty slow. So I'd try to find a way to have both speed and flexibility.

Yes!  And you don't need virtual functions for polymorphism when you have templates.

-Craig