> I have developed a component to handle some security issues. This
> component contains among other stuff a timer that is created in
> component.Create wher I also set interval to 0 and enabled to false.
> If I put this component on a form and compile the application all is
> fine, but when I try to start this minimalistic app then there is
> immediately a very strange exception:
> "Exception EClassNotFound in module Project1.exe at 0000CA2A
> Class TTimer not found."

> Where is it coming from and what can be done about it?

> Final note:
> If I try to remove the component from the form then Delphi locks up
> completely! I cannot even get to Task Manager easily to kill it off.
> I am running Delphi 5 pro on a Win XP-Pro system.

>> I have developed a component to handle some security issues. This
>> component contains among other stuff a timer that is created in
>> component.Create wher I also set interval to 0 and enabled to false.
>> If I put this component on a form and compile the application all is
>> fine, but when I try to start this minimalistic app then there is
>> immediately a very strange exception:
>> "Exception EClassNotFound in module Project1.exe at 0000CA2A
>> Class TTimer not found."

>I believe the problem may be that if you don't use TTimer in your
>application, the class won't be registered. And - and here is the strange
>point - that you have created your component so that a TTimer - property is
>to be read, either when loading your component *or* as a result ogf your
>component creating a TTimer object that is streamed with the form. The
>workaround is to do a RegisterClass(TTimer);. I wouldn't do that if I
>weren't sure about what the trouble was...

>> If I step through the start sequence I get to the Create and the timer
>> property setting and there are no problems. Then after leaving Create
>> I get to the setters for the component properties and there I again
>> meet the timer and it is set successfully. Then at the very end
>> (stepping next on the 'end' line) there is this exception.

>> Where is it coming from and what can be done about it?

>> Final note:
>> If I try to remove the component from the form then Delphi locks up
>> completely! I cannot even get to Task Manager easily to kill it off.
>> I am running Delphi 5 pro on a Win XP-Pro system.

>Creating a component that can actually be removed without bombing is one of
>the more challenging tasks in delphi. ;-) The only tougher one is to make it
>survive deleting a *referenced component*.
>- You'll have to read your code again, asking yourself: "What about this
>reference, will it allways be valid ?"
>The "classic" error is when 2 components reference each other, and these
>references are not "enforced" by notifications (see TComponent's methods:
>FreeNotifier / Notification).
>--
>Bj?rge S?ther
>bjorge@hahaha_itte.no

>But you have a TTimer created by your component, OK ?
>If creating this component results in a TTimer object being inserted in the
>form's components list, then it will be streamed. That is the reason for
>your error, it tries to read a TTimer component from the .dfm resource. It
>should be created without being inserted in *any* 'components' list (Owner =
>nil !). Or - it should be a published property...then I believe class
>registration will be taken care of "by magic".
>--
>Bj?rge S?ther
>bjorge@hahaha_itte.no

> >"Bo Berglund" <bo.bergl...@telia.com> skrev i melding
> >news:3ce17eb4.1242644125@news.telia.net...
> >> I 'solved' my problem by adding a dummy TTimer to the same Data Module
> >> where I had placed the security component. After this there were no
> >> more exceptions. Of course I don't need the timer, but its presence
> >> stops the exceptions....

> >But you have a TTimer created by your component, OK ?
> >If creating this component results in a TTimer object being inserted in
the
> >form's components list, then it will be streamed. That is the reason for
> >your error, it tries to read a TTimer component from the .dfm resource.
It
> >should be created without being inserted in *any* 'components' list
(Owner =
> >nil !). Or - it should be a published property...then I believe class
> >registration will be taken care of "by magic".
> >--
> Hmm,
> I don't understand the statements above (I am by far no Delphi
> *expert*....).
> Here is my component declaration, can you see where I am off? (The
> purpose of the component is to encapsulate the use of a Sentinel
> hardware key, and the timer is intended as an independent key checker
> at a predetermined interval)

> TSentinelAGI = class(TComponent)
> private
> { Private declarations }
>  FSentinelPacket : RB_SPRO_APIPACKET;
>  FOnAlarm: TAlarmEvent;
>  FTimer: TTimer;

>We need the line with TTimer.Create() to see how this is done.

>A tip: You don't need a TTimer component, it's s easy to use SetTmer /
>KillTimer WinAPI calls as a TTimer replacement (TTimer is a wrapper around
>this functionality).

>--
>Bj?rge S?ther
>bjorge@hahaha_itte.no

> >Hi !

> >We need the line with TTimer.Create() to see how this is done.

> >A tip: You don't need a TTimer component, it's s easy to use SetTmer /
> >KillTimer WinAPI calls as a TTimer replacement (TTimer is a wrapper
around
> >this functionality).

> >--
> >Bj?rge S?ther
> >bjorge@hahaha_itte.no

> OK, here is the constructor:

> constructor TSentinelAGI.Create(AOwner: TComponent);
> begin
> inherited Create(AOwner);
> SetAppNumber(1); {To set the default value}
> FTimer := TTimer.Create(Application);