I'm making a class template that only works with strings, so I thought it'd be good to instantiate each template with char, wchar, and dchar right in the template's module so that when it's compiled it'll be part of the .obj file and won't have to compile it for every other project that uses it. However, I get an error reproducible with this:

module test;

class A(T)
{
	version(broken)
	{
		class B
		{
			T blah() { return t; }
		}
	}

	T t;
}

mixin A!(int);

int main()
{
	A!(int) a = new A!(int)();
	return 0;
}

If what I want to do makes sense, how should I be doing it?

On Wed, 16 Dec 2009 07:25:39 +0100, Mike L. <sgtmuffles@myrealbox.com> wrote:

> I'm making a class template that only works with strings, so I thought it'd be good to instantiate each template with char, wchar, and dchar right in the template's module so that when it's compiled it'll be part of the .obj file and won't have to compile it for every other project that uses it. However, I get an error reproducible with this:
>
> module test;
>
> class A(T)
> {
> 	version(broken)
> 	{
> 		class B
> 		{
> 			T blah() { return t; }
> 		}
> 	}
> 	
> 	T t;
> }
>
> mixin A!(int);
>
> int main()
> {
> 	A!(int) a = new A!(int)();
> 	return 0;
> }
>
> If what I want to do makes sense, how should I be doing it?

It makes sense. Seems to be another compiler bug, but I have
no good overview of which (might even be a new one).
This compiles and runs:

class A(T)
{
    version(broken)
    {
        class B
        {
            // Explicitly state which t we're talking about.
            T blah() { return this.outer.t; }
        }
    }

    T t;
}

mixin A!(int);

int main()
{
    A!(int) a = new A!(int)();
    return 0;
}


-- 
Simen

Mike L. wrote:
> I'm making a class template that only works with strings, so I thought it'd be good to instantiate each template with char, wchar, and dchar right in the template's module so that when it's compiled it'll be part of the .obj file and won't have to compile it for every other project that uses it. However, I get an error reproducible with this:
> 
> module test;
> 
> class A(T)
> {
> 	version(broken)
> 	{
> 		class B
> 		{
> 			T blah() { return t; }
> 		}
> 	}
> 	
> 	T t;
> }
> 
> mixin A!(int);
> 
> int main()
> {
> 	A!(int) a = new A!(int)();
> 	return 0;
> }
> 
> If what I want to do makes sense, how should I be doing it?

AFAIK it works if you do

alias B!(int) Something;

If you want to get the above code to work, use template A(T) instead of class A(T) + mixin.

Simen kjaeraas Wrote:

> On Wed, 16 Dec 2009 07:25:39 +0100, Mike L. <sgtmuffles@myrealbox.com> wrote:
> 
> > I'm making a class template that only works with strings, so I thought it'd be good to instantiate each template with char, wchar, and dchar right in the template's module so that when it's compiled it'll be part of the .obj file and won't have to compile it for every other project that uses it. However, I get an error reproducible with this:
> >
> > module test;
> >
> > class A(T)
> > {
> > 	version(broken)
> > 	{
> > 		class B
> > 		{
> > 			T blah() { return t; }
> > 		}
> > 	}
> > 
> > 	T t;
> > }
> >
> > mixin A!(int);
> >
> > int main()
> > {
> > 	A!(int) a = new A!(int)();
> > 	return 0;
> > }
> >
> > If what I want to do makes sense, how should I be doing it?
> 
> It makes sense. Seems to be another compiler bug, but I have
> no good overview of which (might even be a new one).
> This compiles and runs:
> 
> class A(T)
> {
>      version(broken)
>      {
>          class B
>          {
>              // Explicitly state which t we're talking about.
>              T blah() { return this.outer.t; }
>          }
>      }
> 
>      T t;
> }
> 
> mixin A!(int);
> 
> int main()
> {
>      A!(int) a = new A!(int)();
>      return 0;
> }
> 
> 
> -- 
> Simen

Thanks for the reply, that seems to be working for my project too, but the code gets really ugly really fast. Should I submit a bug report?

--Mike L.

Mike L. <sgtmuffles@myrealbox.com> wrote:

> Thanks for the reply, that seems to be working for my project too, but the code gets really ugly really fast. Should I submit a bug report?

Please do. Even if it has a workaround, it's still a bug.

-- 
Simen

Mike L. <sgtmuffles@myrealbox.com> wrote:

> Simen kjaeraas Wrote:
> 
>> On Wed, 16 Dec 2009 07:25:39 +0100, Mike L. <sgtmuffles@myrealbox.com> wrote:
>> 
>> > I'm making a class template that only works with strings, so I thought it'd be good to instantiate each template with char, wchar, and dchar right in the template's module so that when it's compiled it'll be part of the .obj file and won't have to compile it for every other project that uses it. However, I get an error reproducible with this:
>> >
>> > module test;
>> >
>> > class A(T)
>> > {
>> >  version(broken)
>> >  {
>> >   class B
>> >   {
>> >    T blah() { return t; }
>> >   }
>> >  }
>> > 
>> >  T t;
>> > }
>> >
>> > mixin A!(int);
>> >
>> > int main()
>> > {
>> >  A!(int) a = new A!(int)();
>> >  return 0;
>> > }
>> >
>> > If what I want to do makes sense, how should I be doing it?
>> 
>> It makes sense. Seems to be another compiler bug, but I have
>> no good overview of which (might even be a new one).
>> This compiles and runs:
>> 
>> class A(T)
>> {
>>      version(broken)
>>      {
>>          class B
>>          {
>>              // Explicitly state which t we're talking about.
>>              T blah() { return this.outer.t; }
>>          }
>>      }
>> 
>>      T t;
>> }
>> 
>> mixin A!(int);
>> 
>> int main()
>> {
>>      A!(int) a = new A!(int)();
>>      return 0;
>> }
>> 
>> 
>> -- 
>> Simen
> 
> Thanks for the reply, that seems to be working for my project too, but the
code gets really ugly really fast. Should I submit a bug report?
> 
> --Mike L.
> 

As grauzone said, you have to use an alias, or you could use a template. but the
code above just does the same old templated class instantiation, you can leave
out the mixin A!(int); line completely.
As far as I understand it a template is always evaluated at least once for each
type T. So perhaps if you used it in the module that declares it the compiler
would detect that it doesn't need to compile it again but I'm not convinced of
that because the instance is in a different module.

-Rory

Rory McGuire Wrote:

> Mike L. <sgtmuffles@myrealbox.com> wrote:
> 
> > Simen kjaeraas Wrote:
> > 
> >> On Wed, 16 Dec 2009 07:25:39 +0100, Mike L. <sgtmuffles@myrealbox.com> wrote:
> >> 
> >> > I'm making a class template that only works with strings, so I thought it'd be good to instantiate each template with char, wchar, and dchar right in the template's module so that when it's compiled it'll be part of the .obj file and won't have to compile it for every other project that uses it. However, I get an error reproducible with this:
> >> >
> >> > module test;
> >> >
> >> > class A(T)
> >> > {
> >> >  version(broken)
> >> >  {
> >> >   class B
> >> >   {
> >> >    T blah() { return t; }
> >> >   }
> >> >  }
> >> > 
> >> >  T t;
> >> > }
> >> >
> >> > mixin A!(int);
> >> >
> >> > int main()
> >> > {
> >> >  A!(int) a = new A!(int)();
> >> >  return 0;
> >> > }
> >> >
> >> > If what I want to do makes sense, how should I be doing it?
> >> 
> >> It makes sense. Seems to be another compiler bug, but I have
> >> no good overview of which (might even be a new one).
> >> This compiles and runs:
> >> 
> >> class A(T)
> >> {
> >>      version(broken)
> >>      {
> >>          class B
> >>          {
> >>              // Explicitly state which t we're talking about.
> >>              T blah() { return this.outer.t; }
> >>          }
> >>      }
> >> 
> >>      T t;
> >> }
> >> 
> >> mixin A!(int);
> >> 
> >> int main()
> >> {
> >>      A!(int) a = new A!(int)();
> >>      return 0;
> >> }
> >> 
> >> 
> >> -- 
> >> Simen
> > 
> > Thanks for the reply, that seems to be working for my project too, but the
> code gets really ugly really fast. Should I submit a bug report?
> > 
> > --Mike L.
> > 
> 
> As grauzone said, you have to use an alias, or you could use a template. but the
> code above just does the same old templated class instantiation, you can leave
> out the mixin A!(int); line completely.
> As far as I understand it a template is always evaluated at least once for each
> type T. So perhaps if you used it in the module that declares it the compiler
> would detect that it doesn't need to compile it again but I'm not convinced of
> that because the instance is in a different module.
> 
> -Rory
> 

So it sounds like my best bet is to just make a bogus alias. I guess I probably couldn't do something like mixin A!(int) and mixin A!(char), because each would create a class named A and there would be a naming conflict.

--Mike L.