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In article <b3vdgg$1f8t$1@digitaldaemon.com>, Walter says...
>
>Maintenance.
>
>www.digitalmars.com/d/changelog.html
>

<quote>
Added covariant function return types
</quote>

Have you documented this anywhere?

Yeah, what is a covariant function return type?

Sean

"Walter" <walter@digitalmars.com> wrote in message news:b3vdgg$1f8t$1@digitaldaemon.com...
> Maintenance.
>
> www.digitalmars.com/d/changelog.html

"Sean L. Palmer" <seanpalmer@directvinternet.com> escreveu na mensagem news:b40568$1tur$1@digitaldaemon.com...
> Yeah, what is a covariant function return type?
>
> Sean
>
> "Walter" <walter@digitalmars.com> wrote in message news:b3vdgg$1f8t$1@digitaldaemon.com...
> > Maintenance.
> >
> > www.digitalmars.com/d/changelog.html

You can redefine the return type to be "more specific". That means a subclass can override a inherited method and change the return type to a subtype of the original method.

class A {
    A self() {
        return this;
    }
}
class B : A {
    B self() { // covariant return type
        return this;
    }
}

http://sern.ucalgary.ca/courses/SENG/609.03/W98/Abadi/AbadiCh2.html#2.6


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"Patrick Down" <Patrick_member@pathlink.com> wrote in message news:b404ce$1tff$1@digitaldaemon.com...
> <quote>
> Added covariant function return types
> </quote>
>
> Have you documented this anywhere?

Documentation? Huh? <g>

www.digitalmars.com/d/function.html

In article <b3vdgg$1f8t$1@digitaldaemon.com>, Walter says...
>
>Maintenance.
>
>www.digitalmars.com/d/changelog.html
>
>

" Added covariant function return types."

Very cool!  Yet another thing that is just plain broken in C++, fixed in D.

Dan

"Dan Liebgold" <Dan_member@pathlink.com> wrote in message news:b40b5v$21pv$1@digitaldaemon.com...
> " Added covariant function return types."
>
> Very cool!  Yet another thing that is just plain broken in C++, fixed in
D.

But C++ supports covariant function return types. Or is something broken about it that I'm missing? Oddly, C# does not support it, nor does Java. I'd intended to make this work in D for a while, I just was buried in other things. I've been looking at adding 'virtual types', too.

In article <b40d29$23a9$1@digitaldaemon.com>, Walter says...
>
>But C++ supports covariant function return types. Or is something broken about it that I'm missing? Oddly, C# does not support it, nor does Java. I'd intended to make this work in D for a while, I just was buried in other things. I've been looking at adding 'virtual types', too.
>
>

Hmmm, I guess they slipped that in to the C++ design when I wasn't looking. Do you know when it was added?  It seems to have been discussed as recently as a few years ago.

Dan

Walter wrote:

> But C++ supports covariant function return types. Or is something broken about it that I'm missing? Oddly, C# does not support it, nor does Java. I'd intended to make this work in D for a while, I just was buried in other things. I've been looking at adding 'virtual types', too.
> 

Both C# and Java plan to have 'em in future releases.

How would virtual types fit in with templates?

In article <b3vdgg$1f8t$1@digitaldaemon.com>, Walter says...
>
>Maintenance.
>
>www.digitalmars.com/d/changelog.html
>

Are there plans to support initializing arrays with function literals, like this:

//------------------------------------------------//
typedef void function (char*) print_proc;

print_proc functbl[4] = [
(print_proc)function void (char * text) { printf(" %s,\n", text); },
(print_proc)function void (char * text) { printf(" [%s],\n", text); },
(print_proc)function void (char * text) { printf("%s,\n", text); },
(print_proc)function void (char * text) { printf(" {%s},\n", text); },
];

void test () {
for (int i = 0; i < tbl.length; ++i)
functbl[i]("nonsense");
}
//------------------------------------------------//

Currently, the compiler complains with "non-constant expression __anonymous". Perhaps its the above code has an error?

This will work if I separate out the definitions of the functions and name them, then put the names in the array.

Dan