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Remy Lebeau (TeamB)
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 Posted: Fri Feb 06, 2004 6:41 am Post subject: Re: How to avoid AV in the IDE when Component are deleted |
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"Asger Jørgensen" <Asger.Pnotthis (AT) AJ-World (DOT) dk> wrote
| Quote: | if i delete either one of thes components i get an AV and
i have to kill the Builder from the task manager in order
to get on with my work, not good..
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Please show your actual code. You are most likely mismanaging your pointers
correctly.
Gambit
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Remy Lebeau (TeamB)
Guest
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| Posted: Fri Feb 06, 2004 7:49 pm Post subject: Re: How to avoid AV in the IDE when Component are deleted |
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"Asger Jørgensen" <Asger.Pnotthis (AT) AJ-World (DOT) dk> wrote
| Quote: | The code i a lot bigger, but below is one getter and a setter +
the __property, i memset the FInputs[16] to 0 in the constructor.
snip |
You are maintaining pointers to external component instances. At no time in
your setter method are you registering your component to be notified when
any of those external instances are freed so that you can remove your
reference to it. You did not indicate where the AV is actually occuring
(did you even step through your code yet), but you are most likely trying to
access a pointer from your array after it has already been freed since you
did not update your references.
Assuming TAJInput is derived from TComponent, you should be calling the
instance's FreeNotification() method, and then having your component
override its own inherited Notification() method. For example:
class TAJ_InputModule : public TWhatever
{
private:
TAJInput* FInputs[16];
void __fastcall setInput00(TAJInput* Value);
//...
protected:
virtual void __fastcall Notification(TComponent* AComponent,
TOperation Operation);
//...
};
void __fastcall TAJ_InputModule::setInput00(TAJInput* Value)
{
#if (__BORLANDC__ >= 0x0550)
if( FInputs[0] != NULL )
FInputs[0]->RemoveFreeNotification(this);
#endif
FInputs[0] = Value;
if( FInputs[0] != NULL )
FInputs[0]->FreeNotification(this);
}
void __fastcall TAJ_InputModule::Notification(TComponent* AComponent,
TOperation Operation)
{
if( Operation == opRemove )
{
for(int x = 0; x < 16; ++x)
{
if( FInputs[x] == AComponent )
FInputs[x] = NULL;
}
// update your component as needed...
}
// specify the name of the base class you are actually using
TWhatever::Notification(AComponent, Operation);
}
Gambit
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Remy Lebeau (TeamB)
Guest
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| Posted: Sat Feb 07, 2004 1:35 am Post subject: Re: How to avoid AV in the IDE when Component are deleted |
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"Asger Jørgensen" <Asger.Pnotthis (AT) AJ-World (DOT) dk> wrote
| Quote: | I thought i did at design time when deleting one of the referenced
components.
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You didn't say whether the AV was occuring in your own code or not, only
that one was occuring in general.
| Quote: | The IDE might do so but i'm not
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Again, have you actually stepped through your code to find out what is
actually happening?
Is your component still displayed in the Object Inspector at the time when
you delete one of the external components? Or do you ever click on your
component to display it after deleting one of the external components? If
yes to either question, then the Object Inspector is going to re-query your
properties, which in turn will access your properties, which are then
returning pointers from your array. If you do not update your array
properly, you are going to return invalid pointers to the Object Inspector.
So of course it is going to crash until that scenerio.
Gambit
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Remy Lebeau (TeamB)
Guest
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| Posted: Sat Feb 07, 2004 2:56 am Post subject: Re: How to avoid AV in the IDE when Component are deleted |
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"Asger Jørgensen" <Asger.Pnotthis (AT) AJ-World (DOT) dk> wrote
| Quote: | Since it all happend when working in the IDE (no App running)
i can't step through the code.
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Yes, you can. Please read the "Testing installed components" topic in the
help file.
Gambit
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