Why not move cast to the standard library?

[downs]

Jeremie Pelletier wrote:
> downs wrote:
>> Jeremie Pelletier wrote:
>>> grauzone wrote:
>>>> Andrei Alexandrescu wrote:
>>>>> downs wrote:
>>>>>> Andrei Alexandrescu wrote:
>>>>>>> downs wrote:
>>>>>>>> With all the neat template tricks we have in 2.0, and since we're
>>>>>>>> widely redefining the syntax anyway, why not deprecate the current
>>>>>>>> cast syntax and move it into object.d as a library function?
>>>>>>>>
>>>>>>>> So instead of cast(Foo) bar; you would say cast!Foo(bar); .. save
>>>>>>>> on a
>>>>>>>> keyword and demonstrate language power at the same time.
>>>>>>>>
>>>>>>>> What sez ye?
>>>>>>> What would the implementation look like?
>>>>>>>
>>>>>>> Andrei
>>>>>> Unions, and LOTS of static ifs. :)
>>>>> Unions won't work for casting class objects and interfaces because
>>>>> those do pointer adjustments. I think cast must be a primitive.
>>>> When casting interfaces and objects, the primitive cast just calls
>>>> into runtime (functions like _d_dynamic_cast etc.). I don't see a
>>>> reason why cast implemented as templated function couldn't call those
>>>> runtime functions directly.
>>>>
>>>>> Andrei
>>> What about cast(int) or cast(string) and whatnot then? You'd have
>>> cast!A(B) for classes and cast(int) for values, that would be backwards.
>>>
>>> Jeremie
>>
>> What about cast!int could _not_ be done as a function?
> 
> I don't want to call into functions for simple value casts. If I want
> safe casts I use to!int. It may get inlined in release code, but think
> of the debug overhead it would generate.
> 
> The current way is great as it is, cast() for straightforward unsafe
> casting and to!(T)() for safe casting. This is exactly what makes D
> attractive to me, the choice between safe and unsafe alternatives.

What debug overhead?

With current casts, all the logic is in the compiler - where you can't get at it. Moving it into the library can only make this better.

There is nothing about cast that I can see that requires dedicated compiler assistance.

Furthermore, consider it a testcase - if a trivial function like that isn't inlined, _something_ is wrong :)