On 4/05/2015 9:46 a.m., Robert M. Münch wrote:
Hi, I have now played a around couple of hours (reading everything I could find) to get something to work, but I think I'm missing some basic concepts/understanding. Maybe someone can enlighten me how these things work. I thought that some code from David Nadlinger is what I'm searching for but don't know how to exactly make use of it.Here is the code: I want to filter out some of the "allMembers" and use them in my code for a switch/final to check that call cases that were not filtered are covered. Trying to build the enum for the switch/final statement. auto org_rules = TypeTuple!(__traits(allMembers,BolSource)); static assert(!isTypeTuple!(org_rules)); template startsNotWith(T,char C){ static if (T[0] != C){ enum startsNotWith = true; } else { enum startsNotWith = false; } } template StaticFilter(alias pred, T...) { static if (T.length == 0) { alias TypeTuple!() StaticFilter; } else static if (pred!(T[0])) { alias TypeTuple!(T[0], StaticFilter!(pred, T[1 .. $])) StaticFilter; } else { alias StaticFilter!(pred, T[1 .. $]) StaticFilter; } } alias startsNotWithp = startsNotWith!(T,"p"); // doesn't compile: Error: undefined identifier T alias rules = StaticFilter!(startsNotWithp, org_rules); While playing with this a couple of questions came up: 1. How do predicates get their argument(s)? I saw code where only the predicate was mentioned but no arguments. So, I assume there is some behind-the-curtain-magic going on. I read about things like "a == b" where I can reference 'a and 'b in a string. 2. "enum startsNotwith = false" So this is the return syntax for a CTFE for "return(true)" ? 3. TupleType is a very missleading name when you are learning these things, because the tuple can hold values as well. Or is there a more extensive explanation for the name I don't get? 4. Are there any tutorials about CTFE? This seems to be a very powerful but not so easy to use feature of D, but documentation is quite limited. Thanks a lot.
Have you looked at my book? https://leanpub.com/ctfe
