On Saturday, 24 November 2012 at 20:34:39 UTC, comco wrote:
I have the following snippet:
struct A(alias Method)
{
string s;
this(Method method) {
method(s); // 5
}
}
struct B
{
this(int i) { }
void opCall(string s) { }
}
void main() {
A!B(B(0));
}
This code fails to compile with the following errors:
test.d(5): Error: constructor test.B.this (int i) is not
callable using argument types (string)
test.d(5): Error: cannot implicitly convert expression (this.s)
of type string to int
test.d(17): Error: template instance test.A!(B) error
instantiating
shell returned 1
It looks like the compiler is confusing the `method` instance
parameter with the `Method` class.
If I replace line 5 with `method.opCall(s);` it compiles.
Can you explain this behaviour please?
struct A(alias Method) is a template taking in some to be defined
type named Method. I'm not sure why "alias" is there, you can
remove it.
A!B(...) defines a struct A with B typed in as Method, so call to
method(s); is the same as B(string) but there's no B.this(string)
defined for B, causing the compiler to complain.
method.opCall(s); is B.opCall(s) which is defined, and that is
why it will compile.
--rt
