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Has a form already been loaded?

Posted on 2001-08-22
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Last Modified: 2012-05-04
Is there a way of telling whether or not a form has already been loaded?

I'm writing an app with various forms that the user can open, but I only want the user to be able to open each form once. If it's already open, I just want to bring it to the front instead of loading another copy of it.

Cheers
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Question by:riccohb
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Accepted Solution

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kretzschmar earned 200 total points
ID: 6413413
use findcomponent or iterate through the screen.forms-list
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Expert Comment

by:kretzschmar
ID: 6413427
or was it application.forms?
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Expert Comment

by:CrazyOne
ID: 6413517
if Assigned(TheForm) then
 TheForm.Show
else begin
 TheForm := TForm.Create(nil);
 TheForm.Show;
end;

make sure you free the form before you the app terminates.


The Crazy One
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LVL 27

Expert Comment

by:kretzschmar
ID: 6413548
assigned will not work in all cases :-(
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Expert Comment

by:CrazyOne
ID: 6413579
Hi meikl
Really hmm please explain. I haven't found it to be a problem when dealing with forms internal to the application. :>)
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Expert Comment

by:kretzschmar
ID: 6413643
crazy,

just try

...
form1 := tform1.create(self);
form1.free;
if assigned(form1) then  //you will go into the then way
...

better way
...
form1 := tform1.create(self);
FreeAndNil(form1);
if assigned(form1) then  //you will not go into the then way
...

its just that assigned isn't other than objectvar <> nil and free do not nil the objectvar

riccohb,

glad to helped you,
thanks for the points :-)

meikl ;-)
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Expert Comment

by:CrazyOne
ID: 6413815
Ah hah and there you go. I forgot that I always set the form variable to nil when freeing it so that is why I don't have a problem. I just got in the habit of doing it that way that I forgot about it and assumed that the nil was automatic. Duh. hehehe

Thanks meikl for the reminder. :>)
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Expert Comment

by:kretzschmar
ID: 6416420
:-))
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