On Tue, 04 Aug 2009 01:30:29 +1000, Daniel Keep <daniel.keep.li...@gmail.com> wrote:
> > >grauzone wrote: >> Don wrote: >>> Ary Borenszweig wrote: >>>> http://www.prowiki.org/wiki4d/wiki.cgi?LanguageDevel/DIPs/DIP6 >>> >>> This looks like a solution in search of a problem. What's the problem >>> being solved? >> >> Attaching additional data to types, that can't be specified otherwhere. >> This should help with metaprogramming-like stuff. >> >> For example serialization. How do you specify that a field shouldn't be >> part of the serialized data? Java has an extra keyword attribute like >> "transient" (comes from before attributes were introduced). C# uses what >> we call annotation in this thread. How would you do this in D? > >struct Foo >{ > int serialise_me, dont_serialise_me, or_me; > > alias Tuple!("dont_serialise_me", "or_me") IgnoreForSerialisation; >} > >Or, if you'd rather have a less hacky interface: > >struct Foo >{ > int serialise_me, dont_serialise_me, or_me; > > mixin IgnoreForSerialisation!("dont_serialise_me", "or_me"); >} You can even use a mixin per member: struct Foo { mixin Persistent!("field", "field-as-it-is-named-in-db"); int field; mixin Persistent!("field2"); mixin Serializable!("field2"); int field2; } It would be nice (and that is unlikely to happen) if the compiler could rewrite struct Foo { @Persistent("db_field") @Serializable int field; } to struct Foo { int field; mixin Persistent!("field", "db_field"); mixin Serializable!("field"); }
