digitalmars.D.learn - Using alias parameters with class members in CTFE (related to UDAs)
- Johannes Pfau (27/27) Jul 23 2013 Does anyone know why this code is not working?
- Andrej Mitrovic (4/6) Jul 23 2013 Add 'static' to getAttribute and it will work. I know, it's weird, and
- Johannes Pfau (3/10) Jul 23 2013 Thanks! I already feared I'd have to use some string mixin tricks :-)
Does anyone know why this code is not working? http://dpaste.dzfl.pl/b89e7b3f It seems calling "enum a = __traits(getAttributes, Class.member);" is OK without an instance. But if I wrap the __traits call into another template with alias parameter like this: ----------- auto getAttribute(alias target)() { return __traits(getAttributes, target)[0]; } ----------- I can no longer call it at compile time ("enum b = getAttribute!(Class.member)"). What I want to do ultimately is assigning special values to all class members which have a specific UDA while avoiding runtime overhead as much as possible. In pseudo code: ------------ instance i1; static foreach member in i1 static if i1.hasUDA(UdaType) member = specialValue(); ------------ Should compile down to only this: instance i1; i1.member1 = specialValue(); i1.member2 = specialValue(); i1.member3 = specialValue();
Jul 23 2013
On 7/23/13, Johannes Pfau <nospam example.com> wrote:Does anyone know why this code is not working? http://dpaste.dzfl.pl/b89e7b3fAdd 'static' to getAttribute and it will work. I know, it's weird, and I've seen this sort of workaround used before. I think it's a compiler bug.
Jul 23 2013
Am Wed, 24 Jul 2013 02:13:50 +0200 schrieb Andrej Mitrovic <andrej.mitrovich gmail.com>:On 7/23/13, Johannes Pfau <nospam example.com> wrote:Thanks! I already feared I'd have to use some string mixin tricks :-)Does anyone know why this code is not working? http://dpaste.dzfl.pl/b89e7b3fAdd 'static' to getAttribute and it will work. I know, it's weird, and I've seen this sort of workaround used before. I think it's a compiler bug.
Jul 23 2013