Throw an Exception?

[canalrun]

Hello,
I would like to throw an exception as a means of breaking out of a series of loops as a check for something totally unexpected. I could not find an example or if this is even possible.

Here is some "dream" code. Is something like this possible in B4A? What is the correct syntax?

Try
.....
  .....
    .....
      If (x < 0) Then Throw
    .....
  .....
.....
Catch
  Log("This will never work.")
End Try

Thanks,
Barry.

 

[corwin42]

I haven't tried it but the Threading library has an ExceptionEx object which can throw exceptions.

 

[kickaha]

Why not seperate the block of loops into a function, and then to break out of them all you need to do is return. You can use a return value to check if it returned due to an error.

 

[Erel]

You can also do something like:

If x < 0 Then ThrowError


Sub ThrowError
 Dim i As Int
 i = "sdf"
End Sub

 

[canalrun]

Thanks.
Using ExceptionEx is the solution. I found a quick example embedded in code intended as a threading example – very helpful.

I have a bunch of nested loops within a subroutine. If I get an interim result that is negative, this physically makes no sense. I have to abort and exit the subroutine. This is actually a case when Goto's are useful, but using an Exception and Throw is a more structured solution.

Thanks,
Barry.

 

[mc73]

Perhaps, using a flag would do it? For example,

do while flagError=false and flagFinalResult=false
if x<0 then
flagerror=true
else
'continue
flagFinalResult=true
end if
loop
if flagerrror=true then
return
else
'continue
end if

I don't know, just a thought.