http://d.puremagic.com/issues/show_bug.cgi?id=6946
Summary: Compile-time flags generator Product: D Version: D2 Platform: All OS/Version: All Status: NEW Severity: enhancement Priority: P2 Component: Phobos AssignedTo: nob...@puremagic.com ReportedBy: bearophile_h...@eml.cc --- Comment #0 from bearophile_h...@eml.cc 2011-11-13 20:13:10 PST --- A basic version of a compile-time enum-based bit flags: import std.traits: isUnsigned; import std.string: split; import std.conv: text; import std.algorithm: canFind; bool isReservedWord(in string w) { string[] reservedWords = "abstract alias align asm assert auto body bool break byte case cast catch cdouble cent cfloat char class const continue creal dchar debug default delegate delete deprecated do double else enum export extern false final finally float for foreach foreach_reverse function goto idouble if ifloat immutable import in inout int interface invariant ireal is lazy long macro mixin module new nothrow null out override package pragma private protected public pure real ref return scope shared short static struct super switch synchronized template this throw true try typedef typeid typeof ubyte ucent uint ulong union unittest ushort version void volatile wchar while with __FILE__ __LINE__ __gshared __thread __traits".split(); return canFind(reservedWords, w); } string bitFlags(BaseType)(string enumName, string enumItems) if (isUnsigned!BaseType) { assert (enumItems.split().length < (BaseType.sizeof * 8), text("BaseType (", BaseType.stringof, ") doesn't have enough bits to represent all the enumItems.")); string result = text("enum ", enumName, " : ", BaseType.stringof, " {\n"); foreach (i, flag; enumItems.split()) { assert(!isReservedWord(flag), text("enum '", flag, "' is a D keyword.")); result ~= text(" ", flag, " = (1 << ", i, "),\n"); } return result ~ "}"; } // example usage: mixin(bitFlags!size_t("MyEnum", "A B C D")); //mixin(bitFlags!ulong("MyEnum", "A B C D")); // writeln bug void main() { import std.stdio; writeln(MyEnum.C); } This code lacks many handy features, including safety features when you combine flags with MyEnum.A|MyEnum.B, but for a basic usage, if you have many flags, it seems better than not using it. Note: in this simple implementation the first enum (here MyENum.A) equals to 2^0 = 1, so there is no enum for zero. Change this if you want. I'd probably like a function like isReservedWord() too in Phobos. Here the reservedWords array is not static because I need to call isReservedWord() at compile time too. Even if flags are sometimes more complex than the ones this function generates, I think something like this (but improved) is useful in Phobos for the common basic situations. -- Configure issuemail: http://d.puremagic.com/issues/userprefs.cgi?tab=email ------- You are receiving this mail because: -------