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POWhat is the rationale behind the syntax chosen to declare template friends?
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copied!<p>Declaring template function friends involves some incredibly unintuitive syntax, even for C++! What is the rationale behind the choice of syntax for the extra <code><></code> needed? Wouldn't it make more sense to use the <code>template</code> keyword?</p> <p>For those that don't know about this, here is an example of what you might try to do:</p> <pre><code>template <typename T> class Foo { int x; friend void bar(Foo<T>); }; template <typename T> void bar(Foo<T> f) { std::cout << f.x; } </code></pre> <p>If you try to call <code>bar(Foo<T>())</code>, you will get linker errors.</p> <p>To solve this, you have to forward declare <code>bar</code> (and therefore <code>Foo</code>) and then stick an oddly placed <code><></code> in the friend declaration.</p> <pre><code>template <typename T> class Foo; template <typename T> void bar(Foo<T>); template <typename T> class Foo { int x; friend void bar<>(Foo<T>); // note the <> (!?) }; template <typename T> void bar(Foo<T> f) { std::cout << f.x; } </code></pre> <p>My question is, what is the rationale behind the <code><></code> syntax? Wouldn't it be more intuitive to use the <code>template</code> keyword or something along those lines?</p> <p>EDIT: To clarify, <strong>I already know <em>why</em> the <> is required, what I want to know is why they chose to use <> to disambiguate it instead of some other more intuitive syntax.</strong></p>

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