8.5 Afternotes

Ru-Brd

The general concept and syntax of C++ templates have remained relatively stable since their inception in the late 1980s. Class templates and function templates were part of the initial template facility. So were type parameters and nontype parameters.

However, there were also some significant additions to the original design, mostly driven by the needs of the C++ standard library. Member templates may well be the most fundamental of those additions. Curiously, only member function templates were formally voted into the C++ standard. Member class templates became part of the standard by an editorial oversight.

Friend templates, default template arguments, and template template parameters are also relatively recent additions to the language. The ability to declare template template parameters is sometimes called higher-order genericity . They were originally introduced to support a certain allocator model in the C++ standard library, but that allocator model was later replaced by one that does not rely on template template parameters. Later, template template parameters came close to being removed from the language because their specification had remained incomplete until very late in the standardization process. Eventually a majority of committee members voted to keep them and their specifications were completed.

Ru-Brd