pmarkov
asked on
Close Forms
Hello
I want to pervent creation of the form if the form has already created.
I have put this in my application:
if Not Assigned(PaymentForm) then
PaymentForm := TPaymentForm.Create(Self);
PaymentForm.Show;
and:
procedure TPaymentForm.FormClose(Sen
var Action: TCloseAction);
begin
Action := caFree;
PaymentForm := nil;
end;
and everything is OK.
BUT! How can I close the form if Error occured when the form is creating during TPaymentForm.FormCreate precedure executiing?
Example:
procedure TPaymentForm.FormCreate(Se
begin
try
....
....
ERROR
....
except
there I want to close the form! HOW?
end;
Thaks
I want to pervent creation of the form if the form has already created.
I have put this in my application:
if Not Assigned(PaymentForm) then
PaymentForm := TPaymentForm.Create(Self);
PaymentForm.Show;
and:
procedure TPaymentForm.FormClose(Sen
var Action: TCloseAction);
begin
Action := caFree;
PaymentForm := nil;
end;
and everything is OK.
BUT! How can I close the form if Error occured when the form is creating during TPaymentForm.FormCreate precedure executiing?
Example:
procedure TPaymentForm.FormCreate(Se
begin
try
....
....
ERROR
....
except
there I want to close the form! HOW?
end;
Thaks
ASKER CERTIFIED SOLUTION
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hmm, frodo,
looks hazardous,
what is if i use a second instance of the tform-object,
which is not form1 and will freed before?
and if the onCreate-Event is fired,
the object is already properly created,
a exception in this event-procedure would
not cause an automatically destroying
meikl ;-)
looks hazardous,
what is if i use a second instance of the tform-object,
which is not form1 and will freed before?
and if the onCreate-Event is fired,
the object is already properly created,
a exception in this event-procedure would
not cause an automatically destroying
meikl ;-)
Yes, the second form is a good question. But, as I sow form PMarkov's question he's not going to create the same form again if it is created:
"I want to pervent creation of the form if the form has already created".
If that was not the case, then his code is blowing up too:
" Action := caFree;
PaymentForm := nil;"
I'm just using Form1 instead of PamentForm :)
And about if the form is created properly or not... I don't care. The main thing here is that ALWAYS after the destruction the pointer becoms "nil".
And about is it hazardous. Theoreticaly - yes. If you have more than one such form. But PMarkov wants to check if PaymentForm = nil. And I make PaymentForm := nil :)
Rgds,
Frodo
"I want to pervent creation of the form if the form has already created".
If that was not the case, then his code is blowing up too:
" Action := caFree;
PaymentForm := nil;"
I'm just using Form1 instead of PamentForm :)
And about if the form is created properly or not... I don't care. The main thing here is that ALWAYS after the destruction the pointer becoms "nil".
And about is it hazardous. Theoreticaly - yes. If you have more than one such form. But PMarkov wants to check if PaymentForm = nil. And I make PaymentForm := nil :)
Rgds,
Frodo
As a basic rule it is not good to play with the instance in a class method. The disadvantages: you are blowing if (1) you have more than one instance, (2) inherit the class, (3) change the instance, (4) other cases. The solution is to use "self" as an interface to the instance.
But our case is special one.
(1) don't have more than one instance
(2) the class is not likely to be inherited
(3) the instance name is used elsewhere, so we're blowing anyway (on change of the name!)
(4) no comment :)
And using "self" doesen't help. None cares of it. Even more, "self := nil" is a great joke, even if we needed it ;-)
Rgds,
Frodo
But our case is special one.
(1) don't have more than one instance
(2) the class is not likely to be inherited
(3) the instance name is used elsewhere, so we're blowing anyway (on change of the name!)
(4) no comment :)
And using "self" doesen't help. None cares of it. Even more, "self := nil" is a great joke, even if we needed it ;-)
Rgds,
Frodo
ASKER
What about if I put CLOSE in Except statement and PaymentForm := nil in TPaymentForm.FormDestroy?
Thanks
Thanks
Hi all!
I prefer the following way: When I need to perform some initialization/finalizatio
Best regards, Ivo.
I prefer the following way: When I need to perform some initialization/finalizatio
Best regards, Ivo.
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procedure TPaymentForm.FormCreate(Se
begin
try
....
....
ERROR
....
except
release;
end;