Bug 6921 – Request for a 'static final switch' statement

I've often come across cases where I find it'd be handy to have a different constructor based on a passed-in template enum parameter: enum Options { Some, Many, All } class OptionManager(Options O) { static if(O == Options.Some) { alias TypeTuple!(int) TP; } else static if(O == Options.Some) { alias TypeTuple!(int, int, int) TP; } else static if(O == Options.Some) { alias TypeTuple!(int, int, int, int, int, int) TP; } else { static assert(0); } public this(TP params) { // ... } } However, this necessitates a static if-else chain, as shown. It would be quite handy to have a static final switch variant for cases like the above. Would this be something easy to implement in the D language?

Do you mean something like this? It's handy: enum Options { Some, Many, All } class OptionManager(Options opt) { static final switch(opt) { case Options.Some: alias TypeTuple!(int) TP; break; case Options.Many: alias TypeTuple!(int, int, int) TP; break; case Options.All: alias TypeTuple!(int, int, int, int, int, int) TP; break; } public this(TP params) { // ... } }

It would also be nice to have a static final switch on a type tuple. Essentially every type in the type tuple must have an equivalent case. I've ran across a few bugs in my code due to the fact that I forgot a static if (T == sometype). It just fails silently. This happens when new types are added.