https://issues.dlang.org/show_bug.cgi?id=19057
--- Comment #3 from Steven Schveighoffer <schvei...@yahoo.com> --- So the use case for the new style is pretty well discussed and documented (and makes a lot of sense). The use cases for the old style are not discussed really. Looks like the only times default parameters were used is when the number of parameters was less than the default (then the variadic template was inferred as an empty list). I can potentially see the benefit there. Can that functionality be duplicated with the new mechanism? That is the main question we have to answer. If it can, then the deprecation period can be relatively short, with a nice message on how to rewrite. If not, then I don't know what the right path is. Clearly it's a hugely useful thing to be able to specify default parameters for line and file without doing it in the template list. Johan, do you have some sample code to show a good use case for the old way? --