interface I { }
class C: I { }

I object = new C;
assert(typeid(object) == typeid(C)); // fails

Is this normal or is it a bug?
Note, that the same works fine in case of a base class, rather then an
interface.

-- 
Bye,
Gor Gyolchanyan.

On Friday, 30 November 2012 at 10:05:21 UTC, Gor Gyolchanyan wrote:
> interface I { }
> class C: I { }
>
> I object = new C;
> assert(typeid(object) == typeid(C)); // fails
>
> Is this normal or is it a bug?
> Note, that the same works fine in case of a base class, rather then an
> interface.

It works according to spec. Object is expression of type interface I, so no dynamic type search is performed.

So the interfaces aren't supposed to hold a TypeInfo? That doesn't sound right. That makes interfaces useless in a very large set of use cases.


On Fri, Nov 30, 2012 at 2:55 PM, Maxim Fomin <maxim@maxim-fomin.ru> wrote:

> On Friday, 30 November 2012 at 10:05:21 UTC, Gor Gyolchanyan wrote:
>
>> interface I { }
>> class C: I { }
>>
>> I object = new C;
>> assert(typeid(object) == typeid(C)); // fails
>>
>> Is this normal or is it a bug?
>> Note, that the same works fine in case of a base class, rather then an
>> interface.
>>
>
> It works according to spec. Object is expression of type interface I, so no dynamic type search is performed.
>



-- 
Bye,
Gor Gyolchanyan.

On Friday, 30 November 2012 at 11:04:10 UTC, Gor Gyolchanyan wrote:
> So the interfaces aren't supposed to hold a TypeInfo? That doesn't sound
> right. That makes interfaces useless in a very large set of use cases.
>

You can find information about interfaces and classes at http://dlang.org/abi.html (interfaces have a pointer to vtbl[] which entries have pointers to TypeInfo). You can also write enhancement request if you consider your proposal worth implementing (but I don't understand what exactly you want).

On 11/30/2012 9:04 PM, Gor Gyolchanyan wrote:
> interface I { }
> class C: I { }
>
> I object = new C;
> assert(typeid(object) == typeid(C)); // fails
>
> Is this normal or is it a bug?

Normal, since the typeids of interfaces are not the same as for classes.

> Note, that the same works fine in case of a base class, rather then an
> interface.

That works, because classes are classes. Classes are not interfaces.

What's the logic in this behavior?


On Sun, Dec 2, 2012 at 1:28 AM, Walter Bright <newshound2@digitalmars.com>wrote:

> On 11/30/2012 9:04 PM, Gor Gyolchanyan wrote:
>
>> interface I { }
>> class C: I { }
>>
>> I object = new C;
>> assert(typeid(object) == typeid(C)); // fails
>>
>> Is this normal or is it a bug?
>>
>
> Normal, since the typeids of interfaces are not the same as for classes.
>
>
>  Note, that the same works fine in case of a base class, rather then an
>> interface.
>>
>
> That works, because classes are classes. Classes are not interfaces.
>
>
>
>


-- 
Bye,
Gor Gyolchanyan.

On Sunday, 2 December 2012 at 19:26:47 UTC, Gor Gyolchanyan wrote:
> What's the logic in this behavior?
>
>
> On Sun, Dec 2, 2012 at 1:28 AM, Walter Bright <newshound2@digitalmars.com>wrote:
>
>> On 11/30/2012 9:04 PM, Gor Gyolchanyan wrote:
>>
>>> interface I { }
>>> class C: I { }
>>>
>>> I object = new C;
>>> assert(typeid(object) == typeid(C)); // fails
>>>
>>> Is this normal or is it a bug?
>>>
>>
>> Normal, since the typeids of interfaces are not the same as for classes.
>>
>>
>>  Note, that the same works fine in case of a base class, rather then an
>>> interface.
>>>
>>
>> That works, because classes are classes. Classes are not interfaces.

Because interfaces don't extend object?

On Saturday, 1 December 2012 at 21:28:05 UTC, Walter Bright wrote:
> On 11/30/2012 9:04 PM, Gor Gyolchanyan wrote:
>> interface I { }
>> class C: I { }
>>
>> I object = new C;
>> assert(typeid(object) == typeid(C)); // fails
>>
>> Is this normal or is it a bug?
>
> Normal, since the typeids of interfaces are not the same as for classes.
>
>> Note, that the same works fine in case of a base class, rather then an
>> interface.
>
> That works, because classes are classes. Classes are not interfaces.

I'm still waiting to see an object that implement an interface but that isn't a class instance.

On Sunday, December 02, 2012 23:17:33 deadalnix wrote:
> I'm still waiting to see an object that implement an interface but that isn't a class instance.

Isn't that the case with the COM stuff? I remember there being something weird about them being interfaces but not classes, which is part of what has screwed over some of the interface-related stuff like opEquals.

- Jonathan M Davis

On 12/3/2012 6:26 AM, Gor Gyolchanyan wrote:
> What's the logic in this behavior?

Think of it this way. An int can be implicitly converted to a long, but they have different typeid's because they are different bits.