11.8 Afternotes

Template argument deduction for function templates was part of the original C++ design. In fact, the alternative provided by explicit template arguments did not become part of C++ until many years later.

Friend name injection was considered harmful by many C++ language experts because it made the validity of programs more sensitive to the ordering of instantiations. Bill Gibbons (who at the time was working on the Taligent compiler) was among the most vocal supporters of addressing the problem, because eliminating instantiation order dependencies enabled new and interesting C++ development environments (on which Taligent was rumored to be working). However, the Barton-Nackman trick required a form of friend name injection, and it is this particular technique that caused it to remain in the language in its current (weakened) form.

Interestingly, many people have heard of the "Barton-Nackman trick," but few correctly associate it with the technique described earlier. As a result, you may find many other techniques involving friends and templates being referred to incorrectly as the "Barton-Nackman trick" (for example, see Section 16.5 on page 299).