version() blocks often require combinations of version identifiers, including union, intersection, negation, else if, and else structures. However, D currently does not allow version expressions to be combined this way. When a programmer wants to write version(A) { ... } version(B) { ... } version(C || D) { ... } else { ... } D instead generates a compiler error, or unintended runtime behavior, or even different behavior based on the current host environment. I think it is reasonable to assume that programmers want to combine version identifiers much like if/else if/else structures, and we should offer this capability to our users.
Currently version statement is optimized for speed, you can have arbitrary logic with static if. --- template Defined(string s) { mixin(`version(`~s~`)enum Defined=true;else enum Defined=false;`); } struct SVersion { alias opDispatch(string s)=Defined!s; } enum Version=SVersion(); int main() { static if(Version.OSX)writeln("running OSX"); else writeln("no"); return 0; } ---
This enhancement request but the language designers are not in favor of it. Anyway it was already opened : https://issues.dlang.org/show_bug.cgi?id=7417 *** This issue has been marked as a duplicate of issue 7417 ***