Code fails with linker error. Why?

[John Colvin via Digitalmars-d-learn]

On Saturday, 4 October 2014 at 10:38:32 UTC, ketmar via 
Digitalmars-d-learn wrote:
> On Sat, 04 Oct 2014 10:27:16 +0000
> John Colvin via Digitalmars-d-learn 
> <digitalmars-d-learn at puremagic.com>
> wrote:
>
>> Sorry, but that's just not how it works. There is no 
>> requirement for the definition of a function to be found in 
>> the same compilation unit as it's declaration.
> is there any possibility to declare *class* *method* in one 
> file and to
> implement it in another? O_O
>
> i doubt so.

Yes, you can. You just have to get the mangling right.

// methodLink.d
class A
{
     void foo();
}

void main()
{
     auto a = new A;
     a.foo();
}

// missingMethod.d
import methodLink;
import std.stdio;

pragma(mangle, A.foo.mangleof)
void foo() { writeln("Hello World"); }

$ dmd missingMethod.d -c
$ dmd methodLink.d missingMethod.o
$ ./methodLink
Hello World