class template specialization and inheritance

[Bruno Medeiros]

mki wrote:
> Bill Baxter Wrote:
> 
>>> For my programming purpose, the important thing is that C(TT:A(T)) is a specialization of C(T), but the suggested C(TT:A(T),T) is _not_.
>> According to the documentation D thinks it is.  Do you have evidence to 
>> the contrary?
> 
> Thanks for your answer, Bill.
> I am quite new to D, and it seems that I got this quite wrong.
> I believed that for a template to be a specialization of another, the number of template parameters must be the same. 
> 
> With this new insight the code of my original problem changes to
> 
> //begin code example
> import std.stdio;
> 
> class A(T) { }
> 
> class B(T) : A!(T) { }
> 
> class C(T) {
>     static void tellMe() {
>         writefln("generic.");
>     }
> }
> 
> class C(TT:A!(T),T) {
>     static void tellMe() {
>         writefln("TT is the same as or derived from A!(T).");
>     }
> }
> 
> void main() {
>     C!(A!(int)).tellMe();
>     C!(B!(int)).tellMe();
>     C!(int).tellMe();
> }
> //end code example
> 
> which still gives (using DMD 2.008)
> 
> T is the same as or derived from A!(TT).
> generic.
> generic.
> 
> where the second line should be "T is the same as or derived from A!(TT)." in my opinion.
> Am I still doing something wrong, or is this a bug?
> 
>> Sadly the argument deduction (IFTI) implementation is not very complete. 
>>   It only works in very specific situations.
> 
> Thats bad.
> I'm writing heavily templated generic code, currently in C++ with its sometimes very painful template syntax. I hoped that I could switch to D.
> 
> But an incomplete argument deduction implementation is worse than the C++ template syntax.
> 
> ~mki

Seem my comments to your bug report. I don't think it's a bug, but 
rather an enhancement request, but it's hard to say for sure since (IMO) 
the spec is somewhat murky on matters of template specialization.

There is a workaround there which should work for what you want, unless 
you have some other requisite you didn't mention.

-- 
Bruno Medeiros - Software Developer, MSc. in CS/E graduate
http://www.prowiki.org/wiki4d/wiki.cgi?BrunoMedeiros#D