• Extrawurst (18/18) Apr 16 2008 the documentation states that ref is a storage class for function
• Janice Caron (2/2) Apr 16 2008 How is that a bug? I certainly wouldn't have expected that to compile.
• Regan Heath (8/10) Apr 16 2008 I suspect the confusion arises because 'const' is used as both a storage...
• Robert Fraser (4/19) Apr 16 2008 We need to get rid of const the type modifier and keep const the type
• Christian Kamm (4/6) Apr 16 2008 As the others have pointed out, it is intended behavior: storage classes...

Extrawurst <spam extrawurst.org> writes:

the documentation states that ref is a storage class for function 
parameters. just that this code piece wont compile cause the compiler 
doesn't. const in contrast works in templates too. so if no one has a 
veto i will file this as a bug for dmd.

[CODE]
void call(U...)(void delegate(U) dg, U args)
{
    dg(args);
}

void main()
{
    void plus(ref int x)
    {}

    int val = 2;
    call!(ref int)(&plus,val);

}
[/CODE]

dmd2.012: main.d(13): expression expected, not 'ref'

"Janice Caron" <caron800 googlemail.com> writes:

How is that a bug? I certainly wouldn't have expected that to compile.
You can't pass "storage classes" to templates.

Regan Heath <regan netmail.co.nz> writes:

Janice Caron wrote:
 How is that a bug? I certainly wouldn't have expected that to compile.
 You can't pass "storage classes" to templates.

I suspect the confusion arises because 'const' is used as both a storage 
class and as a type modifier.

eg.

const int a = 5;  //storage class
void foo(const int a) {} //type modifier

and you can pass type modifiers to templates.

Regan

Robert Fraser <fraserofthenight gmail.com> writes:

Regan Heath wrote:
 Janice Caron wrote:
 How is that a bug? I certainly wouldn't have expected that to compile.
 You can't pass "storage classes" to templates.

 
 I suspect the confusion arises because 'const' is used as both a storage 
 class and as a type modifier.
 
 eg.
 
 const int a = 5;  //storage class
 void foo(const int a) {} //type modifier
 
 and you can pass type modifiers to templates.
 
 Regan

We need to get rid of const the type modifier and keep const the type 
constructor as the only way to do it. That would solve the return-type 
const problem, too

Christian Kamm <kamm.incasoftware shift_at_left.de> writes:

Extrawurst Wrote:
     call!(ref int)(&plus,val);
 dmd2.012: main.d(13): expression expected, not 'ref'

As the others have pointed out, it is intended behavior: storage classes are
only valid in function parameter declarations and thus can't be passed to a
template as a type parameter. 

You can pass 'ref int' within a type tuple using variadic template arguments
for some reason, but I'm pretty sure that's useless (unless you resort to
string mixins). See bugs 1818, 1411 and 1424 for related issues.

Christian