On Sunday, 18 March 2012 at 06:15:16 UTC, Ali Çehreli wrote:
Every template instantiation of a set of template parameters
becomes a distinct type than any other set of template
parameters.
In other words, Tuple!(double, char) and Tuple!(int, char) are
distinct types. For all the compiler knows, Tuple is a user
type and only the user should define whether they are
compatible. Tuple does not define opCast() to covert from
Tuple!(int,char) to Tuple!(double,char). I guess it could have
been defined. (?)
A solution is to explicitly perform the conversion:
import std.conv;
// ...
stack ~= to!(Tuple!(double, char))(tuple(10, '+'));
(An alias would make that easier to read. :/).
It seems long and ugly...
I also write:
Tuple!(uint, double delegate(double, double))[char] Operators;
Operators['+'] = tuple(1u, (x, y) => x + y);
It doesn't work. I have to write:
Operators['+'] = tuple(1u, cast(double delegate(double,
double))(x, y) => x + y);
Much longer :/
Someone tell me that this is called SFINAE problem in C++
http://www.open-std.org/jtc1/sc22/wg21/docs/papers/2008/n2634.html
I tried this C++ code:
stack<pair<double, char> > s;
s.push(make_pair(10, '+'));
It compiles fine with g++.
Any chance to see this being solved in D?
;)
