Constraining template's function parameter signature
Tommi
tommitissari at hotmail.com
Thu Jun 14 05:57:26 PDT 2012
I'm trying to constrain a struct template based on a parameter
that's supposed be a function with a certain signature. Difficult
to explain, easier just to show the problem:
module pseudorange;
struct PseudoInputRange(T, alias advance)
//The next line doesn't compile
//if (is(typeof(advance(T.init)) == void))
{
private:
T m_front;
T m_end;
public:
this(T begin, T end) pure nothrow
{
m_front = begin;
m_end = end;
}
@property immutable(T) front() const pure nothrow
{
return m_front;
}
void popFront() pure nothrow
{
advance(m_front);
}
@property bool empty() const pure nothrow
{
return m_front == m_end;
}
}
//...
module main;
import std.stdio;
import std.range;
import pseudorange;
int main(string[] argv)
{
alias PseudoInputRange!(int, (ref int x) {++x;}) MyRange;
static assert(isInputRange!MyRange);
foreach (x; MyRange(1, 11))
{
writeln(x);
}
stdin.readln();
return 0;
}
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