• Frank Benoit (8/8) Nov 05 2007 Is there a way to make a generic T const free?
• Janice Caron (6/7) Nov 05 2007 I think this works
• Robert DaSilva (12/23) Nov 07 2007 Almost,

Frank Benoit <keinfarbton googlemail.com> writes:

Is there a way to make a generic T const free?

E.g. there is this function:

T[] reverse(T)(T[] str ){...}

auto res1 = reverse( "abc".dup ); // T=char
auto res2 = reverse( "abc" );     // T=invariant(char)

If reverse now needs a mutable T in its implementation, how can it be
implemented?
Without explicitely testing for the known types char/wchar/dchar?

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

On 11/5/07, Frank Benoit <keinfarbton googlemail.com> wrote:
 Is there a way to make a generic T const free?

I think this works

template(T) { typedef T Mutable; }
template(T:const(T)[]) { typedef T[] Mutable; }

Then Mutable!(T) is the mutable equivalent of T

That's from memory, but I've had something like that working.

Robert DaSilva <spunit262.nospam gmail.com> writes:

Janice Caron wrote:
 On 11/5/07, Frank Benoit <keinfarbton googlemail.com> wrote:
 Is there a way to make a generic T const free?

 
 I think this works
 
 template(T) { typedef T Mutable; }
 template(T:const(T)[]) { typedef T[] Mutable; }
 
 Then Mutable!(T) is the mutable equivalent of T
 
 That's from memory, but I've had something like that working.

Almost,

template Mutable(T)
{
	alias typeof(T) Mutable;
}

template Mutable(T : T[])
{
	alias typeof(T)[] Mutable;
}

typedef creates a new distinct type, and for some reason you need to use
typeof to remove the invariantness from T.