Privileged Instruction?

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Privileged Instruction?

Hi my friends.

I have a number of frames in my app and I would like to change the properties of controls by calling a procedure. So, I have this code:

procedure TModifiedFrame.setProperties(ClassName, SomeProperty: string;
Value: Integer);
var
i: integer;
PropInfo: PPropInfo;
Component: TComponent;
begin
for i := 0 to ComponentCount - 1 do
begin
Component := Components[i];
if (Component is TControl) and ((Component.ClassName = trim(ClassName))
or (Trim(ClassName) = 'AllComponents')) then
begin
PropInfo := GetPropInfo(Component.ClassInfo, SomeProperty);
if Assigned(PropInfo) then
SetOrdProp(Component, PropInfo, Integer(Value));
end;
end;
end;

I call it like this: MyFrame.setProperties('TLabel','Height',5) to test it.

I am facing two Qs here:

1. I get a run-time error: Privileged instruction at (addr) at SetOrdProp line. Am I trying to access something I shouldn't?

2. I can see how the GetPropInfo and setOrdProp work with zero-level properties (eg. 'Height', 'Visible', etc) but do they retrieve data for other level of properties such as TextSettings.FontColor?

Thanks

Comments

  1. John KouraklisOctober 29, 2016 at 9:57 AM

    Ok, I use RTTI and I do it like this:

    var
    context: TRttiContext;
    aProp: TRttiProperty;
    begin
    ....
    if (tmpComponent is TControl) and ((tmpComponent.ClassName = trim(ClassName))
    or (Trim(ClassName) = 'AllComponents')) then
    begin
    prop:=context.GetType(tmpComponent.ClassType).GetProperty(Trim(SomeProperty));
    if Assigned(prop) then
    prop.SetValue(tmpComponent, Value);
    end;
    ....

    The above works for uniquely identified properties such as Height, Text and even FontColor (although it is TextSettings.FontColor). Now, I can't access properties with same names. For example, I want to go to TextSettings.Font.Size but it conflicts with the Size property. Anyone knows how to do this using RTTI?

    ReplyDelete
  2. David SchwartzOctober 29, 2016 at 1:23 PM

    Just out of curiosity, what version of Delphi are you using?

    ReplyDelete
  3. John KouraklisOctober 29, 2016 at 2:43 PM

    David Schwartz 10.1 with update 1. Does the demo work in previous versions?

    ReplyDelete

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