On Thursday, 27 March 2014 at 17:42:24 UTC, Luís Marques wrote:
Could this be made to work?
struct S(T)
{
T x;
this(T x)
{
this.x = x;
}
}
void main()
{
int x = 42;
auto s = S(x); // fails to deduce T
}
This is usually done via a "constructor function", that's the
name of your struct, but with a lower case start letter. EG:
//----
/// Some struct parameterized on T.
struct MyStruct(T)
{
T x;
this(T x)
{
this.x = x;
}
}
/// convenience to build a MyStruct
auto myStruct(T)(T t)
{
return MyStruct!T(t);
}
void main()
{
int x = 42;
auto s = myStruct(x); // succeeds in deducing T
}
//----
This "old standing" trick predates D, and comes from C++, with
functions such as
//----
namespace std
{
pair<T1, T2> make_pair<T1, T2>(T1 t1, T2 t2)
{
return pair<T1, T2>(t1, t2);
}
}
//----
