[fpc-devel] "Default" discussion for SmartPointers etc

[Sven Barth]

Am 27.07.2016 21:04 schrieb "Maciej Izak" <hnb.code at gmail.com>:
>
>
> 2016-07-27 15:33 GMT+02:00 Jonas Maebe <jonas.maebe at elis.ugent.be>:
>>
>> It would seem better to me that you do have to add something after your
proxy object (specify a field, call a method, use proxyobject[x], ...)  to
get the proxied value. Just like with a class, where "instance" by itself
can never refer to the default property (it's always "instance[x]").
>
>
> In that case SmartPtr/SmartObj/Nullable type has no sense for me. The
basic purpose is excluded. You can do that today by using for example
proxyobject._.foo();
>
> To get rid of @@/@@@ we can use typecast + new type kind. With "proxy"
type, Sven proposition has more sense:
>
> === code begin ===
> {$MODE DELPHI}
>
> type
>   TRawSomeSmart<T> = record
>   private
>     Instance: T;
>     ... // normal record
>   end;
>
>   TSomeSmart<T> = proxy to TRawSomeSmart<T>.Instance;
>
> var
>   ptr: pointer;
>   // PTypeInfo(TypeInfo(ni)).Kind = tkProxy
>   ni: TSomeSmart<Integer>;
>   np: TSomeSmart<TProcedure>;
> begin
>   ptr := @ni; // pointer to ni.Instance
>   ptr := @TSomeSmart<Integer>(ni); // pointer to ni
>
>   ptr := @@np; // pointer to np.Instance
>   ptr := @np   // pointer to procedure
>   ptr := @TSomeSmart<TProcedure>(np); // pointer to np
> end;
> === code end ===

Hmm, not that bad either. At least then it would be absolutely clear that
TSomeSmart is something special and not an ordinary record.

Regards,
Sven
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