On Sunday, February 24, 2013 04:33:29 Martin wrote:
> import std.stdio;
>
> class TestClass(T)
> {
> private:
> __gshared TestClass[] globalInstances;
> public:
> this()
> {
> globalInstances ~= this;
> }
>
> void test()
> {
> writeln("Address of variable globalInstances is: 0x",
> globalInstances.ptr);
> }
>
> }
>
> void main(string[] args)
> {
>
> TestClass!(int) t1 = new TestClass!(int);
> TestClass!(string) t2 = new TestClass!(string);
>
> t1.test;
> t2.test;
>
> readln;
>
> }
>
> Outputs:
> Address of variable globalInstances is: 0x4F3F80
> Address of variable globalInstances is: 0x4F3F60
>
> Which I guess makes sense since there's seperate globalInstances
> variables generated per template instance of the class. I want to
> store ALL instances, no matter if it's a TestClass!(int) or
> TestClass!(string) though.
>
> Should I just use a __gshared void*[] globalInstances outside of
> the template and cast when necessary or is there an easier way
> that I'm too stupid to see? It's really late here...
Every instance of a template is a completely different type than every other
instance. They have no more relation to each other than
class Foo {}
and
class Bar {}
do. Remember that when you're instantiating a template, your literally
generating code. It's basically a lot of copying and pasting by the compiler.
If you want to store something for all instantiaties of a template, then it's
going to need to be done outside of the template. However, I'd point out that
in general, keeping track of every instance of a class isn't a good idea, and
treating each instantiation of a template as if it had a relation to other
instantiations of a template is also generally a bad idea. You may indeed have
a use case where it makes sense, but my first inclination would be to suggest
that you rethink whatever you're doing.
- Jonathan M Davis
