Examples:¶

template <typename T>
char const *prty() { return __FUNCSIG__; }

namespace foo { struct bar; }
int main() { std::cout << prty<foo::bar>() << std::endl; }

template <typename T>
char const *prty() { return __PRETTY_FUNCTION__; }

namespace foo { struct bar; }
int main() { std::cout << prty<foo::bar>() << std::endl; }

(the actual function used for typename retrieval is named wnaabi::pretty_function::c_str)

Using __PRETTY_FUNCTION__ this way enables access to the names of user defined types, complete with namespaces. This method can be used to retrieve strings for any type, but wnaabi uses other tricks to handle non-class types since the output of __PRETTY_FUNCTION__ is highly compiler dependent. Since the macro is expanded at compile time, constexpr functions can be used to trim the clutter.

wnaabi::get_typename returns the name of a user defined type without decoration by copying only the substring which contains the typename. Since the original string literal resulting from macro expansion is unreferenced, optimizing compilers can drop it from the resulting binary. The resulting buffer for foo::bar is exactly 8 char- not even the terminating null.

The string used to indicate residence in an anonymous namespace is compiler dependent (MSVC: foo::`anonymous-namespace'::baz, Clang: foo::(anonymous namespace)::baz, gcc: foo::(anonymous)::baz). These are filtered out by wnaabi::get_typename, yielding foo::baz. NB: wnaabi will probably never introduce a normalized anonymous scope string- foo::__anonymous::baz precludes the existence (in one translation unit, anyway) of foo::baz and foo::__anonymous1::baz. Therefore (IMHO), an anonymous scope string seems like pure bloat. For boffins who know when this would actually be handy/necessary, see this discussion of type-sorted polymorphic sets.

__PRETTY_FUNCTION__ can be used to retrieve the name of an instantiation of a template class, but the arrangement of arguments following the template name is also compiler dependent. wnaabi uses __PRETTY_FUNCTION__ only to retrieve the template name and defers formatting of template arguments to other functions. Although this allows wnaabi to guarantee the formatting of template types, it makes general support for non-type template parameters impossible.