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sQuid

Templated Functions

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If I include the following header file
  
template <typename Z> class bar {
	public :
		Z a;

	bar(Z b) : a(b) { }
	
	~bar() {}
};

template <typename Z> bar<Z> ram(Z a) {
	return bar<Z>(a);
}

bar<int> ewe(int a) {
	return bar<int>(a);
}
  
in seperate source files the linker naturally complains about the multiply defined symbol ewe. However it doesn''t complain about the templated function ram. Why is this exactly?

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Because ram doesn''t ''exist'' (as far as the linker is concerned) until it is used and given a type for Z.
Template functions are molds to make functions from - instructions for the compiler which constructs a new function for each type you give it.

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Guest Anonymous Poster
I''m pretty sure that...
(not positive)
templates are not actual code until they are used somewhere, ie they are instianited (sp?). In fact, as I remember, in the Standard, I don''t think the template is even supposed to be compiled
So, because Ewe isn''t a template function, then it _is_ defined, and multiple defines are obviously not allowed..
however for Ram, it doesn''t exist until it is used, so you could indeed include it many many times

I think.

C++Freak
(so I''m too lazy to change my password so I can log in again)

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