Why I get no identifier for declarator .... ?
mixin are useless in this case but that is a minimal example of my problem.
tlvar is type of TL so i do not see where is the problem.
Code also on dpaste, same error with dmd or ldc.
Thanks for your help
import std.stdio;
import std.typecons;
struct Data{
int x;
int y;
}
template getcode(T)
{
mixin(`
alias TL = Tuple!(
int,"x",
int,"y"
);
`);
TL tl;
mixin(`
tl.x = 10;
tl.y = 5;
`);
}
void main()
{
getcode!Data;
writeln( tl.x );
}
Your problem is that templates can only contain declarations, not statements or expressions. This is the offending code:
mixin(`
tl.x = 10;
tl.y = 5;
`);
These are assignments, not declarations. This is why you get the weird error message "Error: no identifier for declarator tl.x". The compiler thinks you are trying to make a declaration of a variable, and it can't find the type "tl.x"... or something like that. The solution is to set the value of the tuple inline, like so:
template getcode(T)
{
mixin(`alias TL = Tuple!(int, "x", int, "y");`);
TL tl = TL(10, 5);
}
Or, to better match your original code:
template getcode(T)
{
mixin(`alias TL = Tuple!(int, "x", int, "y");`);
TL tl = mixin(`TL(10, 5)`);
}
There is now another problem. In main, where you instantiate the template, you will get the error "Error: getcode!(Data) has no effect". This is because a template instantiation on its own is not a declaration. You have to either alias it to a symbol, or mix it in using a mixin statement.
Aliasing it to a symbol will allow you to access the declarations inside the template through that symbol, and mixing it in puts the template's declarations into the scope it's instantiated in. I would recommend the first option, as it's more hygenic. You shouldn't use mixin unless you absolutely have to.
void main()
{
//Error: getcode!(Data) has no effect
//getcode!Data;
//Ok
//mixin getcode!Data;
//writeln( tl.x );
//Ok
alias Code = getcode!Data;
writeln( Code.tl.x );
}
You can see my corrected version of your code here: