Why Does Invoking a Member Function Template from a Templated Function Require the `template` Keyword?

Member Function of Templated Class Invocation from Templated Function

In the provided code snippet, invoking a member function template from within another template results in a compilation error. Specifically, the code attempts to call A<T>::f<3>() from within g<T>(). However, this fails due to a syntax issue.

To resolve this, the template keyword must be explicitly specified before the member function invocation. This is because according to the C '03 Standard 14.2/4, when the name of a member template specialization appears after a postfix-expression or qualified-id that depends on a template parameter, the member template name must be prefixed with the template keyword.

Therefore, the following code is correct:

<code class="cpp">template&lt;class T&gt; void g()
{
   A&lt;T&gt; a;
   a.template f&lt;3&gt;();  // Explicitly specify 'template' keyword
}</code>

By adding the template keyword, the compiler can correctly identify that f is a member template of the A class template, and it can successfully call A<T>::f<3>().

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