On Friday, 14 December 2012 at 20:14:29 UTC, Philippe Sigaud
wrote:
On Fri, Dec 14, 2012 at 1:18 AM, bearophile
<[email protected]>wrote:
Fit to be added to Phobos?
Maybe, I don't know. People seem to ask for this quite
regularly.
Here is a slightly improved version, what do you think?
template isTemplatedType(Type...) if (Type.length == 1)
{
mixin("alias " ~ Type[0].stringof ~ " U;");
static if (is(Type[0] _ == U!Args, Args...))
enum isTemplatedType = true;
else
enum isTemplatedType = false;
}
template TemplateArity(Type...) if (Type.length == 1 &&
isTemplatedType!(Type[0]))
{
mixin("alias " ~ Type[0].stringof ~ " U;");
static if (is(Type[0] _ == U!Args, Args...))
enum TemplateArity = Args.length;
}
template TemplateArgs(Type...) if (Type.length == 1 &&
isTemplatedType!(Type[0]))
{
mixin("alias " ~ Type[0].stringof ~ " U;");
static if (is(Type[0] _ == U!Args, Args...))
alias Args TemplateArgs;
}
void main()
{
alias Tuple!(int, double) T;
writeln(TemplateArity!T);
writeln(TemplateArgs!T.stringof);
writeln(isTemplatedType!T);
}
Oops ;/ How do I get the number of type arguments if I don't know
them yet? I know this sort of seems wrong but somehow, to know
how to alias the class I need to know it's number of arguments.
(I don't think it makes too much sense with the type system but
not sure how to solve the following problem without it:
http://forum.dlang.org/thread/[email protected]#post-yhhtuojlsgiykyrfhngl:40forum.dlang.org)
