Such examples speak more to C++ templates as a mechanism for capturing usage patterns in a convenient form, thus effectively creating a special-purpose, domain-

Such examples speak more to C++ templates as a mechanism for capturing usage patterns in a convenient form, thus effectively creating a special-purpose, domain-specific language, than they speak to such templates as a meta-language. "Meta" means "information about information", so a meta-language in this case would describe the mechanisms used to capture such patterns, not the patterns themselves. I do meta every day, meta-meta often, and triple-meta occasionally. The rules language for my Expert System is a true meta-language, because I designed it to (among other things) specify the manipulation of computer languages. So its domain knowledge is about the nature of computer languages and how to automate their assessment / analysis, transformation / re-engineering, translation, and generation. To give a real-life example, we used our Expert System to automate the translation of complex compiler front- and back-end code from a proprietary system language to C++ for a major computer manufacturer. The translation rules don't really care what the code is doing; they care how the code is doing it. The compiler team created new templates and classes to provide the functionality their system language had that C++ doesn't, and we adjusted our translation rules to ensure that the translated code invokes those templates and classes in a clear, effective, efficient, and readable way.