miv
asked on
List of events
How do I fire events stored in a TList ?
What exactly do you mean ? Do you want to fire multiple event handlers for one event stored in a TList, or event handlers for different events stored in this list ?
ASKER
option 2
Yo,
maybe you could explain a bit why you need to store the event handlers in a TList. That would help to make a better answer.
Basically it is only typecast. Lets assume that the stored event is a TNotifyEvent, here is a quick example :
TMyObject = class(TObject)
FEventList: TList;
FEventCount: Integer;
constructor Create;
destructor Destroy; override;
procedure SetOnClick(NewValue : TNotifyEvent);
function GetOnClick: TNotifyEvent;
property OnClick: TNotifyEvent read GetOnClick write SetOnClick;
end;
constructor TMyObject.Create;
var Index : Integer;
begin
inherited Create;
FEventList := TList.Create;
FEventCount := 1;
for Index := 0 to FEventCount - 1
do FEventList.Add(nil);
end;
destructor TMyObject.Destroy;
begin
FEventList.Free;
inherited Destroy;
end;
procedure TMyObject.SetOnClick(NewVa lue : TNotifyEvent);
begin
FEventList[0] := @NewValue;
end;
function TMyObject.GetOnClick: TNotifyEvent;
var FEvent : TNotifyEvent;
begin
@FEvent := FEventList[0];
Result := FEvent;
end;
Fireing events would be like the code in GetOnClick, but better check first if the pointer is not nil.
Hope this helps,
Slash/d003303
maybe you could explain a bit why you need to store the event handlers in a TList. That would help to make a better answer.
Basically it is only typecast. Lets assume that the stored event is a TNotifyEvent, here is a quick example :
TMyObject = class(TObject)
FEventList: TList;
FEventCount: Integer;
constructor Create;
destructor Destroy; override;
procedure SetOnClick(NewValue : TNotifyEvent);
function GetOnClick: TNotifyEvent;
property OnClick: TNotifyEvent read GetOnClick write SetOnClick;
end;
constructor TMyObject.Create;
var Index : Integer;
begin
inherited Create;
FEventList := TList.Create;
FEventCount := 1;
for Index := 0 to FEventCount - 1
do FEventList.Add(nil);
end;
destructor TMyObject.Destroy;
begin
FEventList.Free;
inherited Destroy;
end;
procedure TMyObject.SetOnClick(NewVa
begin
FEventList[0] := @NewValue;
end;
function TMyObject.GetOnClick: TNotifyEvent;
var FEvent : TNotifyEvent;
begin
@FEvent := FEventList[0];
Result := FEvent;
end;
Fireing events would be like the code in GetOnClick, but better check first if the pointer is not nil.
Hope this helps,
Slash/d003303
ASKER
Ok, I´ll try to explain exactly what I want:
I have an object which on modification of some vars need to notify all the viewers which is viewing the object.
The viewers has added their "OnReshow" event to the "NotificationList" on the object.
I want to traverse the NotificationList and fire all the events on the list.
But as the list only knows that it is containing pointers, it can´t treat them as events. Have tried typecasting, but get compiler errors everytime...
I have an object which on modification of some vars need to notify all the viewers which is viewing the object.
The viewers has added their "OnReshow" event to the "NotificationList" on the object.
I want to traverse the NotificationList and fire all the events on the list.
But as the list only knows that it is containing pointers, it can´t treat them as events. Have tried typecasting, but get compiler errors everytime...
ASKER CERTIFIED SOLUTION
membership
This solution is only available to members.
To access this solution, you must be a member of Experts Exchange.
ASKER
Hi,
It was to fast to accept that answer.
The FEvent seems to pointing no where (or maybe into the ROM :-) when I fire it...
Any suggestions ?
Michael
It was to fast to accept that answer.
The FEvent seems to pointing no where (or maybe into the ROM :-) when I fire it...
Any suggestions ?
Michael
Yo,
to help you on that I need some sample code where the event list is filled, and where the events are fired.
Slash/d003330
to help you on that I need some sample code where the event list is filled, and where the events are fired.
Slash/d003330
ASKER
Hi,
It´s ok. I created a dummy object with one attribut and added that object to the list instead. That works but´s a bit of a workaround.
I can´t post my code, you´ll need apx. 70000 lines to reconstruct the error :-(
Thanks for the help anyway, you earned your points.
It´s ok. I created a dummy object with one attribut and added that object to the list instead. That works but´s a bit of a workaround.
I can´t post my code, you´ll need apx. 70000 lines to reconstruct the error :-(
Thanks for the help anyway, you earned your points.