Why D const is annoying

[Andrei Alexandrescu]

On 12/10/11 5:11 AM, Walter Bright wrote:
> On 12/10/2011 3:04 AM, Mehrdad wrote:
>> On 12/10/2011 3:01 AM, Walter Bright wrote:
>>> On 12/10/2011 2:34 AM, Mehrdad wrote:
>>>> ... and another...
>>>>
>>>> struct Matrix(T, size_t N = 1)
>>>> { public auto mul(Matrix!(T, N) other) const { return this; } }
>>>
>>>
>>> In general, to refer to the current template being expanded from
>>> inside of it,
>>> just give its name, as in:
>>>
>>> Matrix!(T,N) => Matrix
>> That's not the issue.
>>
>> If you say 'int' instead of size_t, it works fine.
>
> That's because
>
> Matrix!(int, cast(int)1)
>
> is considered a different template instantiation (and hence a different
> type) from
>
> Matrix!(int, cast(uint)1)
>
> Instantiation types are based on the arguments' types, not the
> parameters' types.
>
> If you use my suggestion for the shorthand notation, your code will work
> as you expect.

Please let's not deflect the issue. If there's a patentable way to annoy 
an annoyed user even more, this must be it. A bug is a bug is a bug. 
Matrix can _only_ be instantiated with size_t, it says so in the definition:

struct Matrix(T, size_t N = 1) { ... }

THAT IS NOT:

struct Matrix(T, alias N = cast(size_t) 1) { ... }

as the current compiler seems to wrongly implement it. The fact that one 
can actually instantiate it with int or whatnot should first convert the 
int to size_t, and then instantiate the matrix with size_t.

http://d.puremagic.com/issues/show_bug.cgi?id=7090

Thanks Mehrdad.


Andrei