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Create and Destroy events in  a unit?

Posted on 2001-08-16
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Last Modified: 2010-04-06
Hi.

I'm currently writing an app that has loads of different custom Types created in it, so I put them all in a unit to make it easier to share their definitions.

Now what I want to do is create some objects within the unit that are also shared throughout the project.  I need to know how to code an OnCreate event and an OnDestroy event for the unit so that I can create and destroy the objects within the unit.

Could someone advise me please.

Thankyou,

MoonCalf.
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Question by:MoonCalf
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6 Comments
 
LVL 20

Expert Comment

by:Madshi
ID: 6392790
Why not using the initialization / finalization parts of the unit?

unit blabla;

interface

type TObj1 = class ...;
     TObj2 = class ...;

var obj1 : TObj1 = nil;
    obj2 : TObj2 = nil;

implementation

initialization
  obj1 := TObj1.Create;
  obj2 := TObj2.Create;
finalization
  obj1.Free;
  obj2.Free;
end.

Regards, Madshi.
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LVL 1

Author Comment

by:MoonCalf
ID: 6392804
Madshi,

When I tried that I just used showmessage to tell me when the unit opened and when it closed.

I got the one for opening, but not for closing.

???
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LVL 20

Expert Comment

by:Madshi
ID: 6392816
You don't get one for closing only if someone calls TerminateProcess or ExitProcess. If your process ends typically with closing the main form (that is if the code reaches the last line of your *.dpr file), the finalization parts of all units should be executed...

So the big question is: Who closes your application and how?

Regards, Madshi.
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LVL 1

Author Comment

by:MoonCalf
ID: 6392826
I close it either from the sysmenu of the form (or the X in the top right corner) or I press Ctrl-F4.
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Accepted Solution

by:
Madshi earned 45 total points
ID: 6392834
Ooops. ShowMessage doesn't show, if Application.Terminated is true - and it is when running through the finalization parts of your units. Use MessageBox instead, it will show you that your program *does* run through the finalization part...

Regards, Madshi.
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LVL 1

Author Comment

by:MoonCalf
ID: 6392884
That's cool.

Thanks Madshi.
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