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buildingSMART / IFC4.3.x-development

Repository to collect updates to the IFC4.3 Specification
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IfcObject.ObjectType description to take into account PredefinedType may not exist #170

Open SergejMuhic opened 2 years ago

SergejMuhic commented 2 years ago

Probably mostly documentation for IFC4.3. The usage of the attribute shall be modified to feature the possibility of not having a PredefinedType set to USERDEFINED. Modification will follow after we agreed to the course of action.

Moult commented 2 years ago

What's the new proposed behaviour? The concept of storing userdefined in ObjectType has been well established for a while now.

aothms commented 2 years ago

The issue is specifically to the wording

https://github.com/buildingSMART/IFC4.3.x-development/blob/master//docs/schemas/core/IfcKernel/Entities/IfcObject.md#objecttype

... if the enumeration of the attribute PredefinedType is set to USERDEFINED.

Where not every entity has a PredefinedType attribute especially if IfcBuiltElement is now instantiated directly.

@SergejMuhic in the meeting I didn't recall this, but actually there has been some debate on whether BuiltElemProxy should be deprecated. I think in the end in this version it isn't http://ifc43-docs.standards.buildingsmart.org/IFC/RELEASE/IFC4x3/HTML/lexical/IfcBuiltElementProxy.htm I'm not sure if this has much bearing on the issue. It would apply regardless to entities such as IfcDistributionElement

SergejMuhic commented 2 years ago

What's the new proposed behaviour? The concept of storing userdefined in ObjectType has been well established for a while now.

@aothms already explained it nicely. As not every instantiable entity e.g. IfcBuiltElement has a PredefinedType now, there has to be a mechanism available to type these kinds of entities. The mechanism of storing USERDEFINED would remain untouched just extended.

@SergejMuhic in the meeting I didn't recall this, but actually there has been some debate on whether BuiltElemProxy should be deprecated. I think in the end in this version it isn't http://ifc43-docs.standards.buildingsmart.org/IFC/RELEASE/IFC4x3/HTML/lexical/IfcBuiltElementProxy.htm I'm not sure if this has much bearing on the issue. It would apply regardless to entities such as IfcDistributionElement

It has some influence but entities such as IfcBuiltElement still remain that do not have this kind of a typing mechanism mechanism available. As it seems, we might need a concept template to encode and document these kinds of usages on entities without PredefinedType.

Moult commented 2 years ago

Note that issue also mentioned indirectly here