[fpc-devel] restbase.pp LoadFromJSON calling StopRecordPropertyChanges;

[Wayne Sherman]

On Fri, Jan 13, 2023 at 11:48 PM Michael Van Canneyt wrote:
> Markpropertychanged is called in the setter of the properties generated by
> the code generator: Check all generated units.

Thanks for your explanations, it is getting more clear how modified
property tracking is being used.

More clarification please.  MarkPropertyChanged offsets the property
changed index (to TBits) by the ClassParent total property count, but
IsPropertyModified does not take this offset into account.  Consider
this example:

TBaseObject --> TGoogleBaseObject --> TSchema --> TMySchema
TBaseObjectClass = Class of TBaseObject;

If the object is TMySchema, in GetParentPropCount the TBits index gets
offset by (see reference code below):
  TBaseObjectClass(TSchema).GetTotalPropCount;
If the object is TSchema, the TBits index gets offset by:
  TBaseObjectClass(TGoogleBaseObject).GetTotalPropCount;

Questions:
1) Since the ClassParent is always cast as TBaseObjectClass isn't this
the same as just TBaseObjectClass(Self.ClassType)?

2) Doesn't each object already have the parent properties included in
its own properties by inheritance?

3) Why does MarkPropertyChanged offset the index and
IsPropertyModified does not take the offset into account?

Reference for above questions:

class function TBaseObject.GetParentPropCount: Integer;
begin
  if (ClassParent=TBaseObject) or (ClassParent=Nil) then
    Result:=0
  else
    Result:=TBaseObjectClass(ClassParent).GetTotalPropCount;
end;

procedure TBaseObject.MarkPropertyChanged(AIndex: Integer);
begin
  If Assigned(FBits) then
    FBits.SetOn(GetParentPropCount+(AIndex shr IndexShift));
end;

function TBaseObject.IsPropertyModified(Info: PPropInfo): Boolean;
begin
  Result:=Not Assigned(FBits) or FBits.Bits[Info^.NameIndex]
end;

</end reference code>