> You cannot publish records, and this is not planned. > > This is because things like > > MyClass.MyRecord.MyField:=12; > > do not work as one would naively expect. It does work if you use a TPersistent > instead of a record (the very reason the TPersistent class was invented)
Do you mean the trap when "MyField" is actually a property (with possible setter) and "MyClass.MyRecord.MyField:=123" effectively (may) modify a temporary value? I feel this is something a bit independent to being able to publish the records. It is indeed a trap, and can be solved by designing a record to not have any properties/methods that change it's state. The only allowed changes to record state should be directly through the fields. Then the compiler already correctly prevents you from doing "MyClass.MyRecord.MyField:=12;" . We dealt with this in CGE too, see https://castle-engine.io/coding_traps , https://github.com/castle-engine/castle-engine/blob/master/src/base/castlevectors_generic_float_record.inc#L44 . > > However, you can use extended RTTI to access this typeinfo and manipulate the > record. > That works. > Last time I checked, the RTTI information was not generated for records in only the "public" section, and (as per above) the records could not be placed in the "published" section. Is now one of the above possible? :) This would be cool, and it is very desired by Castle Game Engine. To explain more our use-case in CGE: We do use a few records (like for vectors and matrices, TVector3, TCastleColor etc.) and we like to have properties that expose them on object (e.g. "TCastleTransform.Translation:TVector3"). Right now, being able to see this in the object inspector (in Lazarus or in CGE editor) requires a bit of a hack -- we need a class, like TCastleVector3Persistent ( https://github.com/castle-engine/castle-engine/blob/master/src/base/castlevectors_persistent.inc#L92 ), that exposes the record, effectively is synchronized 2-way with TVector3 record. And every time someone wants to expose TVector3 property to the editor, they need to - make the TVector3 property public (and this is what should be used by Pascal developers), - and put the corresponding TCastleVector3Persistent in published. It is possible, but requires some boiler-plate code each time: https://castle-engine.io/custom_components#_publishing_vectors_and_colors . If we could instead just put TVector3 in the published section, and make it exposed in the object inspector (maybe adding some additional code to use RTTI, but that is made *once*, not every time we need to expose TVector3) this would be great :) Regards, Michalis _______________________________________________ fpc-devel maillist - fpc-devel@lists.freepascal.org https://lists.freepascal.org/cgi-bin/mailman/listinfo/fpc-devel
