Exception Handling

[fafalone]

tB could definitely use some basic exception handling. Look at the disassembly of a minimal C try/except block, this seems extremely impractical to do via user code as it needs entries in the PE header directory for exceptions.

But based on how it appears, and correct me if I'm wrong, there's no reason the user code couldn't use very familiar syntax right at home on BASIC...

On Exception GoTo label

There's no compatibility issues as that's never permissible VBx syntax.

Basically what I'm looking to do is protect against things like bad pointers passed by outside callers as in C

__try {
...
} __except(EXCEPTION_EXECUTE_HANDLER) {
...
}

Iirc there are plans to offer more robust error handling with try... But from a syntax view that's major change in both implementation and program structure. This could provide something right at home in the language with an easier back end implementation. Still presumably post 1.0 unless it's dead simple, but hopefully that's on the horizon now.

[mburns08109]

@fafalone

ON exception Goto label ?
How would that be different from On Error Goto x - in programs flow terms?
Would it behave more like a "On exception GoSub label "? (and where would the "Gosub"'s return point be?

Considering this, I'm leaning more towards a new Try...Catch...Finally style of syntax for this (like vb.net, yes).

[fafalone]

It would be pretty much identical to regular error handling, which isn't very different from GoSub. The resume point would, like traditional errors, be the next line for Resume Next, etc.

Try/Catch is a more long term change... I'm not sure if it's a good idea to combine the errors VBx/tB traps (HRESULTs from COM and intrinsic function errors) with exceptions (e.g. access violation from a bad pointer that normally crashes the app). Seems like one of the advanced things you'd want as opt in. And of course the old On Error syntax can't go away so it's not like we're talking about replacing the whole of error handling.