Dealing with painfully long namespace names in headers

Question

Is there anything that can be done about looong symbols that need to be referenced in header files, e.g. ABDEFGHIJ::ZXCBVB::AWEDADSDEM::GFGBKGDF::Tools::Item? I know in header files you aren't supposed to using using because it messes up anybody who includes it.

The only working feature that cleans up after itself that I can even think of would be #define+#undef but that seems terrible.

Is there a new feature that solves this that I'm not aware of? I'm also interested in any popular proposals. Maybe using with a bracketed block syntax, to let me restrict the effect to just my header...?

Answer 1

It's not good practice to have a using namespace using directive at global scope in a header file. There are a number of less drastic things you can do that are fairly benign however.

• Inside an inline or template function in a header, you can use a using directive without affecting anyone else. This saves you having to qualify all the names in a non-trivial function body.
• As Maksim Solovjov suggests, you can use namespace aliases to cut down on typing, with the caveat that a namespace alias at global scope will introduce that alias to anyone including your header so that may not be desirable.
• C++11 introduced type aliases and alias templates which can be used in a header at class scope, function scope or namespace scope (you may still want to avoid using them at global scope) to give a shorter name to types. This is particularly useful when dealing with template types with long names like e.g. std::map<std::string, std::vector<std::function<float(float)>>>
• C++11 and 14 type deduction through the auto keyword can greatly reduce the need to name long types in headers, whether function return types, local variables or parameters to lambdas.
• C++11 decltype can also be useful to avoid saying the names of long types in certain situations.