Access violation reading published read only property

Question

I'm having a problem with Delphi XE to access in designtime a read-only property derived from another component only in cases where the component in question it is a specialized form or datamodule.

I have a "Comp1" component and a "Comp2". In "Comp2" component, have a published reading "Comp1" only property.

Plant the "Comp1" component in the "Form1". I specialize "Form1" generating "Form2". If I try to access the "Comp1" property in "Form2" it creates an "Access Violation".

Only identified this problem in Delphi XE. In Delphi 6, tested and works normally. I did not actually test on newer versions XE3, XE4 or XE5.

In the code below I show the case.

Unit UnTestComp;

Interface

Uses Classes, StdCtrls;

Type
  //Component 1

  TComp1 = Class(TComponent)
  Private
    FNome: String;
    FEdit: TEdit;
    Function GetText: String;
    Procedure SetText(Const Value: String);
  Public
    Constructor Create(AOwner: TComponent); Override;
    Destructor Destroy; Override;
  Published
    Property Nome: String Read FNome Write FNome;
    Property Texto: String Read GetText Write SetText;
  End;


  // Component 2
  TComp2 = Class(TComponent)
  Private
    FComp1: TComp1;
  Protected

  Public
    Constructor Create(AOwner: TComponent); Override;
    Destructor Destroy; Override;
  Published
    Property Comp1: TComp1 Read FComp1;

  End;

Procedure Register;

Implementation

Uses SysUtils, Dialogs;

Procedure Register;
Begin
  RegisterComponents('CompReadOnly Test', [TComp1, TComp2]);
End;

{ TComp1 }

Constructor TComp1.Create(AOwner: TComponent);
Begin
  Inherited;
  FEdit := TEdit.Create(Self);
End;

Destructor TComp1.Destroy;
Begin
  FreeAndNil(FEdit);
  Inherited;
End;

Function TComp1.GetText: String;
Begin
  Result := FEdit.Text;
End;

Procedure TComp1.SetText(Const Value: String);
Begin
  FEdit.Text := Value;
End;

{ TComp2 }

Constructor TComp2.Create(AOwner: TComponent);
Begin
  Inherited;
  FComp1 := TComp1.Create(Self);
  FComp1.Name := 'Comp1';
End;

Destructor TComp2.Destroy;
Begin
  FreeAndNil(FComp1);
  Inherited;
End;

End.

Someone had a similar problem that can share a possible solution?

Answer 1

How not found the cause of the problem. I'm change the property to "public" and when needed access via RTTI. Previously, due to a legacy code, the property was "published" in Delphi 6 because we could only access via RTTI if the property was published. Currently, in Delphi XE, due to the improved features of the RTTI that is no longer needed.

Sample:

  TComp2 = Class(TComponent)
  Private
    FComp1: TComp1;
  Protected

  Public
    Constructor Create(AOwner: TComponent); Override;
    Destructor Destroy; Override;
    Property Comp1: TComp1 Read FComp1;
  End;

Thank you for your attention.