BorlandTalk.com

Sarfraz Bokhari · Guest

Hi group,

Using WinXP, Delphi 7

I have some properties those should be shaed among number of components let
Prop1, Prop2, etc. I want to create a groups of properties and their
implementation and then re-use among serval classes. Please read following
code sample.

Something like this.

type
TMyProperties = class;
private
FProp1 : boolean;
FProp2 : string;
... some other properties of classes types ......
protected
procedure SetProp2(AVal : string);
public

published
Prop1 : boolean read FProp1 write FProp1;
Prop2 : sting read FProp2 write SetProp2;
end;

type
MyControl1 = class(SomeControl1)
private
FMyProp : TMyProperties
FProp3 : integer;
proteced
{what should I do in this procedure or it is not requires.}
procedure SetMyProp( AMyProp : TMyProperties);
published
property MyProperties : TMyProperties read FMyProp write SetMyProp;
end;

type
MyControl2 = class(SomeControl2)
private
FMyProp : TMyProperties
FProp3 : SomeType;
proteced
{what should I do in this procedure or it is not requires.}
procedure SetMyProp( AMyProp : TMyProperties);
published
property MyProperties : TMyProperties read FMyProp write SetMyProp;
end;
implementation
.......
create MyProperties in constructor and Free in destructor .........
......
1. Now what steps should be taken to expose MyProperties in
ObjectInspector because if I click in ObjectInspector, Delphi reports
"unable to expand"

2. Should I create a member, say Ower, so TMyProperties knows to whom it
belongs to or how to get/set the properties of the class in which
TMyProperties exists?

3. I should consider new way. Pease give some examples

Thanks in advance

S. Bokhari

Alain Quesnel · Guest

In addition to making TMyProperties a descendant of TPersistent, you need to
initialize your private field FMyProp in the constructor and free it in the
destructor. And look at the Set methods for MyProp. Like so (untested):

unit Unit2;

interface

uses Classes, Controls, SysUtils;

type

TMyProperties = class(TPersistent)
private
FProp1: boolean;
FProp2: string;
procedure SetProp2(const Value: string);
published
property Prop1 : boolean read FProp1 write FProp1;
property Prop2 : string read FProp2 write SetProp2;
end;

MyControl1 = class(TControl)
private
FMyProp : TMyProperties;
procedure SetMyProp(const Value: TMyProperties);
public
constructor Create(AOwner: TComponent); override;
destructor Destroy; override;
published
property MyProperties : TMyProperties read FMyProp write SetMyProp;
end;

MyControl2 = class(TCustomControl)
private
FMyProp : TMyProperties;
procedure SetMyProp(const Value: TMyProperties);
public
constructor Create(AOwner: TComponent); override;
destructor Destroy; override;
published
property MyProperties : TMyProperties read FMyProp write SetMyProp;
end;

implementation

{ TMyProperties }

procedure TMyProperties.SetProp2(const Value: string);
begin
FProp2 := Value;
end;

{ MyControl1 }

constructor MyControl1.Create(AOwner: TComponent);
begin
inherited;
FMyProp := TMyProperties.Create;
end;

destructor MyControl1.Destroy;
begin
FreeAndNil(FMyProp);
inherited;
end;

procedure MyControl1.SetMyProp(const Value: TMyProperties);
begin
FMyProp.Assign(Value);
end;

{ MyControl2 }

constructor MyControl2.Create(AOwner: TComponent);
begin
inherited;
FMyProp := TMyProperties.Create;
end;

destructor MyControl2.Destroy;
begin
FreeAndNil(FMyProp);
inherited;
end;

procedure MyControl2.SetMyProp(const Value: TMyProperties);
begin
FMyProp.Assign(Value);
end;

end.

--

Alain Quesnel
[email]alainsansspam (AT) logiquel (DOT) com[/email]

www.logiquel.com

"D Whaley" <dwhaley (AT) hs-technologies (DOT) com> wrote

Sarfraz Bokhari · Guest

Thanks,
I will try it next week because I have been assigned another small propject.

I have still one question, in TMyProperties class methods I want to
manipulate parent class properties. How could it possible. Should I write
code something like

procedure Create(AOwer.........)
begin
FMyProp := TMYProperties.Create;
FMyProp.SetParent(Self);

--- but how to manipulate Private Members of "Self" in TMyProperties
methods.
--- or I should consider some other path.
end;

Thanks your reply.
S. Bokhari

"Alain Quesnel" <alainsansspam (AT) logiquel (DOT) com> wrote

Alain Quesnel · Guest

If you want to use the owner of TMyProperties, then that class would have to
inherit from TComponent instead of TPersistent. However, I'm not sure it's
"proper" to do so. And don't confuse Parent and Owner, they are two quite
different concepts.

--

Alain Quesnel
[email]alainsansspam (AT) logiquel (DOT) com[/email]

www.logiquel.com

"Sarfraz Bokhari" <sarfraz_bokhari (AT) yahoo (DOT) com> wrote