Any chance to call Tango as Extended Standard Library

[John Reimer]

Hello Andrei,

> Lars Ivar Igesund wrote:
> 
>> Andrei Alexandrescu wrote:
>> 
>>> Lars Ivar Igesund wrote:
>>> 
>>>> Jason House wrote:
>>>> 
>>>>> Andrei Alexandrescu wrote:
>>>>> 
>>>>>> I'd be curious to find out more about a runtime queryable struct
>>>>>> interface. How would it work? What idioms would it enable?
>>>>>> 
>>>>> I don't know what Lars is thinking of, but I think of struct
>>>>> interfaces as a non-polymorphic / compile-time inheritance. AKA,
>>>>> you can have a struct implement it, but you can't cast it to a
>>>>> base struct/interface.  Outside of defining the struct, I'd expect
>>>>> it to only be usable in templates and is-expressions
>>>>> 
>>>> Nope, I want something that works at runtime. Inheritance
>>>> could/should be non-polymorphic and compile-time, but I want to
>>>> know at runtime that a void* has implemented a given interface.
>>>> 
>>> Consider you can avail yourself of a function:
>>> 
>>> bool implements(Interface)(void* p);
>>> 
>>> What would you do with it?
>>> 
>> Assuming that I (after getting a positive result from a call to the
>> above, and that I have an interface with the member foo) can then
>> safely call p.foo, I could do a lot of stuff that I can't do today.
>> 
> I understand. So essentially you don't want to see whether a void*
> implements an interface, but instead you want to get that interface,
> i.e. obtain the pointers to the functions in the interface as
> implemented by whatever struct that void* stands for. In doing so you
> also claim that all of that is entirely possible to do so at low or no
> cost. After the functions in that interface are obtained, you also
> implicitly claim that they won't hurt performance of the design by
> using indirect calls.
> 
> If my understanding of the above is correct, this is an extraordinary
> claim. It is, in fact, so extraordinary that I'll bite the bullet and
> claim myself that you are thoroughly confused about what you want and
> to what extent it is realizable. My guess is that if you follow your
> idea to its ultimate conclusion, you will be inexorably drawn to
> rediscovering how vtables work and what tradeoffs they embed when
> compared to direct function calls.
> 
> Andrei
> 


I wonder if anybody finds you intimidating in person. :D

-JJR