Implement missing Partials in IFC4x3 schema

[andyward]

A number of 'Partial' class extensions are missing from the IFC4x3 schema. E.g. IfcSitePartial, IfcCompoundPlaneAngleMeasurePartial etc.

Consider if these could be better implemented as extensions on the cross schema interfaces

[WalchAndreas]

Hi,

while porting our application to support Ifc4x3, we encountered problems regarding Properties / Quantities.
The IIfcObject interface fails to provide PhysicalSimpleQuantities / PropertySets / GetElementQuantity() ....

Trying to resolve queries for IIfcProperty, we tested the instance to specific IfcObject (Ifc2x3.Kernel / Xbim.Ifc4.Kernel / Xbim.Ifc4x3.Kernel) implementation, which seems not promising for future versions.

Do you have recommendations to resolve this issue?

[andyward]

Naively we just need to implement (copy - paste) the Partial classes from IFC4 in IFC4x3 schema. E.g. For PhysicalSimpleQuantities etc in IFC4 & 2x3 we have these implemented as helper methods in IfcObjectPartial

But I actually think the better pattern (to save duplicating code) will be to implement as Extension-methods on the 'common' IFC4 interfaces so they can be defined once and used on all schemas. It may have made sense pragmatically to copy when we had 2 schemas but with 3+ it's feels like overhead.

You could even implement these ExtensionMethods yourself as a stop gap if it's blocking you - or send us a PR and we'll incorporate officially.