On Saturday, 22 February 2014 at 14:03:11 UTC, Philippe Sigaud
wrote:
Now what remains is to retstrict create to only take a fun
with *no*
input arguments and a non-void return.
How do I do that?
With a template contraint.
Not tested:
import std.traits: isCallable, ParameterTypeTuple, ReturnType;
auto create(alias fun)(size_t n)
if (isCallable!fun && ParameterTypeTuple!(fun).length == 0
&& !is(ReturnType!fun == void))
{
import std.range: iota, map;
return n.iota.map!(n => fun);
}
Your solution with
ParameterTypeTuple!(fun).length == 0
doesn't work here because currTime takes a defaulted argument.
I believe we need a new std.trait, say arityMin, for this.
Any ideas on how to implement that? Perhaps using
__traits(compiles...?
See also my update at:
https://stackoverflow.com/questions/21954381/range-construction-pattern/21954416?noredirect=1#21954416
