Delphi Programming

and software in general.

Friday, November 12, 2010

Another Generics / RTTI bug. Attributes are ignored in parametrized types.

The output from the code below, shows that you cannot enumerate attributes for properties of a parametrized type such as TOpenClass.

If you close the class as a TDecidedClass = TOpenClass, any attributes declared in TDecidedClass may have enumerable attributes, but the attributes declared for properties in TOpenClass are still not enumerable.

Output from the code:

Properties for TBaseClass
Normal
Blinged [Bling]

Properties for TBaseParam
BlingTFails <- Note the lack of a [Bling] attribute here 

BlingIntFails <- Note the lack of a [Bling] attribute here 
Normal 
Blinged [Bling] 


Properties for TBaseInt 
BlingInt [Bling] 
BlingTFails <- Note the lack of a [Bling] attribute here 
BlingIntFails <- Note the lack of a [Bling] attribute here 
Normal 
Blinged [Bling]


program AttributeFailsForParametricGenericType;

{$APPTYPE CONSOLE}

uses
  ExceptionLog,
  Classes,
  Generics.Defaults,
  RTTI;

type
  Bling = class(TCustomAttribute);

  TBaseClass = class
  private
    function GetBling: Integer;
    function GetNormal: Integer;
    procedure SetBling(const Value: Integer);
    procedure SetNormal(const Value: Integer);
  public
    procedure Inspect;
    property Normal:Integer read GetNormal write SetNormal;
    [bling] property Blinged:Integer read GetBling write SetBling;
  end;

  TBaseParam = class(TBaseClass)
  private
    function GetBlingTFails: T;
    procedure SetBlingTFails(const Value: T);
    function GetBlingIntFails: Integer;
    procedure SetBlingIntFails(const Value: Integer);
  public
    [bling] property BlingTFails:T read GetBlingTFails write SetBlingTFails;
    [bling] property BlingIntFails:Integer read GetBlingIntFails write SetBlingIntFails;
  end;

  TBaseInt = class(TBaseParam)
  private
    function GetBlingInt: Integer;
    procedure SetBlingInt(const Value: Integer);
  public
    [bling] property BlingInt:Integer read GetBlingInt write SetBlingInt;
  end;


{ TBaseClass }

function TBaseClass.GetBling: Integer; begin end;
function TBaseClass.GetNormal: Integer; begin end;

procedure TBaseClass.Inspect;
var
  Context : TRttiContext;
  SourceType : TRttiType;
  SourceProp : TRttiProperty;
  SourceAttribute : TCustomAttribute;
  s : String;
begin
  Context := TRttiContext.Create;
  try
    SourceType := Context.GetType(Self.ClassType);
    Writeln('');
    Writeln(ClassName);

    for SourceProp in SourceType.GetProperties
    do begin
      s := SourceProp.Name;

      for SourceAttribute in SourceProp.GetAttributes
      do begin
        s := s + ' [' + SourceAttribute.ClassName + ']';
      end;
      Writeln(s);
    end;
  finally
    Context.Free;
  end;
end;

procedure TBaseClass.SetBling(const Value: Integer); begin end;
procedure TBaseClass.SetNormal(const Value: Integer); begin end;

{ TBaseParam }
function TBaseParam.GetBlingTFails: T; begin end;
function TBaseParam.GetBlingIntFails: Integer; begin end;
procedure TBaseParam.SetBlingTFails(const Value: T); begin end;
procedure TBaseParam.SetBlingIntFails(const Value: Integer); begin end;

{ TBaseInt }
function TBaseInt.GetBlingInt: Integer; begin end;
procedure TBaseInt.SetBlingInt(const Value: Integer); begin end;


var
  Base : TBaseClass;
  BaseT : TBaseParam;
  BaseInt : TBaseInt;
begin
  Base := TBaseClass.Create;
  Base.Inspect;

  BaseT := TBaseParam.Create;
  BaseT.Inspect;

  BaseInt := TBaseInt.Create;
  BaseInt.Inspect;

  Readln;
end.

Tuesday, November 9, 2010

Programming Windows Phone 7 by Charles Petzold

Microsoft are very keen to get people started on development for Windows Phone 7. So keen that they are giving away the 1013 pages thick eBook version (in PDF or XPS format) of Charles Petzold's Programming Windows Phone 7.

Now, all we need is the ability use Prism :)

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