try... except

[Fernando]

Hi guys.

Is there a way to do this?:

////////////////////////////////////////

try

if MessageDlg('Press Yes or No', mtConfirmation, [MBYES, MBNO], 0) = MRYES then GOtoEXCEPTend;

except
ShowMessage('The user clicked on YES button.');
end;

////////////////////////////////////////

Thank you.

[TheLion]

You can leave out the Try... Except there ... since the MessageDlg is unlikely to fail

[pascal]
if MessageDlg('Press Yes or No', mtConfirmation, [MBYES, MBNO], 0) = MRYES then
Begin
ShowMessage('The user clicked on YES button.');
End
Else
Begin
ShowMessage('The user clicked the NO button.');
End;
[/pascal]


It might be that I misunderstood what you where trying to do, however I don't see the need for try...except in this scenario... If you want to jump from the loop if the user presses the yes / no button you could use the exit command...

[cairnswm]

Yes there is a way to do it but dont - it is really bad coding.

As TheLion Suggests - there are better ways.

[Fernando]

Yes!

But I have other things in mind: Look, let's say I have this code:


try

...

GetMem(p, 10000);
Object.SomeProcedure();
OtherObject.Procedure(10, 10);

open:= OpenSomething();

if open = FALSE then GoToExceptEnd;

...

except
FreeMem(p);
Object.Free;
OtherObject.Free;
CloseSomething();
end;


In this example, I have made calls to 4 procedures/functions: GetMem, SomeProcedure, Procedure and OpenSomething.

If something goes wrong with one of them, I have to free all the resources used by the code. I do that in the except/end statement.

But the problem is that the fourth function (OpenSomething) don't raise exceptions. Instead of this, it returns FALSE or TRUE. If it returns FALSE, I would like the code jump to the Except End to, as if an exception were raised.

Is there a way to do that?

Thank you!

[Sander]

Well, if you really want to, you could try putting it either in a try..finally block(but only if you need to free those things in any case, which I doubt). OR you could put the freeing in a seperate procedure, and do it like this:

try

...

GetMem(p, 10000);
Object.SomeProcedure();
OtherObject.Procedure(10, 10);

open:= OpenSomething();

if open = FALSE then FreeProcedure;
...

except
FreeProcedure;
end;




FreeProcedure;
begin
FreeMem(p);
Object.Free;
OtherObject.Free;
CloseSomething();
end;




But there might be other ways....

[Harry Hunt]

try
AllocateSomeMemory(X);
except
ShowAWarning;
finally
if Assigned(X) then
FreeMemory(X);
end;

[Useless Hacker]

How about raising an exception yourself if the function returns false?

[pascal]try
...
if open = FALSE then raise Exception.Create('open failed');

...

except
FreeMem(p);
Object.Free;
OtherObject.Free;
CloseSomething();
end;[/pascal]

[Fernando]

My god! A lot of solutions! :-)

THank you guys! I enjoyed all the examples!
Fernando