On Thursday, 10 October 2013 at 17:24:37 UTC, H. S. Teoh wrote:
I have a template used for storing compile-time values:
template Def(int x, string y) {
alias impl = TypeTuple!(x,y);
}
How do I define a template isDef that, given some template
alias A,
evaluates to true if A is some instantiation of Def?
template isDef(alias A) {
enum A = ... /* what to put here? */
}
The intent is to be able to write signature constraints like
this:
auto myFunc(alias def)(...)
if (isDef!def)
{
...
}
...
// Pass an instantiation of Def to myFunc
auto x = myFunc!(Def!(1, "abc"))(args);
I tried using std.traits.isInstanceOf but apparently it expects
the
second argument to be an actual type, which doesn't work in
this case
because Def is a typetuple of compile-time values, not an
actual type.
T
I've used this horrible hack to solve this. Not very generic as
you can see:
else static if(T.stringof.length > 13 && T.stringof[0..13] ==
"TupleWrapper!")
