Re: TestError

[BB <adamnt42@xxxxxxxxx>]

Try (😉) thinking this way...

"TRY" disengages the global error handling mechanism for a short time 
(see later). It will allow a command that would/could cause a generic 
error to be raised to proceed to the next command without an error 
"bang" to happen. So... we can test the Error boolean flag and do 
something if or otherwise. Suppose there is an infamous cat in a box, 
now we don't know if it does or does not exist do we? So attempting to 
determine at command line #1,

	01  If ThisCat.Exists then ...

 is indeterminate UNTIL the line is executed. Since ThisCat doesn't 
exist, (ThisCat = Null) then ThisCat.Exists would fail with a null 
object error and the normal error handling would be invoked. But if we

	01 Try ThisCat.Exists
	02 If Not Error then
	03	DoSomethingEvilToTheCat
	04 Else
	05 	CloseBox 	
	06 EndIf

then depending on Error the cat in question will have some bad luck or 
we just close the box until next time.

Global error handling...

is a bit different, lets face it life is bad. Stuff happens. Phone 
operator A deletes your account while you are talking to phone operator 
B, etc etc. Life on planet Gambas is a lot more logical. Something 
happens and suddenly something else doesn't work. And no-one expected 
so. Error.Bang! = true

What the interpreter does is this (sort of).

It looks at the current method block to see if there is a Catch "label". 
If so then it jumps there and does whatever it says. Fine, but if there 
is none it crawls its way majestically up the call stack looking to see 
if there is anyone that can do something about this deplorable lack of 
knickers. If no-one can then the runtime has a bit of a panic and throws 
up (raises a system error).

Important! Finally, there is a thing called Finally. Everybody in the 
call stack can have a Finally block, sort of like famous last words. No 
matter if the object was about to expire from the dreaded dividebyzero 
cancer, it will have its famous last word(s). These will issue no matter 
how hard you try to strangle him beforehand.

I'd better go now. 😅

b