[Mono-list] exceptions and ECMA issues

[Paolo Molaro]

On 08/23/01 Carl R. Witty wrote:
> > Basically it says that if an exception id thrown, control is transfered to the
> > matching catch block [1] and only later to the finally block [2].
> > Partition I, instead, claims that a matching catch block is searched, but
> > before executing it, control is transfered to the finally block
> > (section 11.4.2.2.):
> > 
> > --snip snip--
> > If a match is not found in the current method, the calling method is searched, and so on. If no match is found 
> > the CLI will dump a stack trace and abort the program. If a match is found, the CLI walks the stack back to the 
> > point just located, but this time calling the finally and fault handlers. It then starts the corresponding exception 
> > handler. Stack frames are discarded either as this second walk occurs or after the handler completes, depending 
> > on information in the exception handler array entry associated with the handling block. 
> > --snip snip--
> 
> I think you're misreading the specification here.
> 
> Let me give an example.  (Warning: I don't know C#; this is almost
> certainly not the correct C# exception handling syntax.)
> 
>   try {
>     ...
>     try {
>       throw ...;
>     } finally {
>       // finally handler A
>     }
>   } catch {
>     // catch handler B
>   } finally {
>     // finally handler C
>   }
> 
> My reading of the paragraph you quoted above is that you must execute
> "finally handler A" before executing "catch handler B".  The other
> paragraph you quoted (that I cut from my reply) says you must execute
> "catch handler B" before "finally handler C".

That is the problem. Partition I is quite clear that the finally handler
needs to be execute before the catch handler is executed.
What if the code was simply:

>   try {
>     ...
>     throw ...;
>   } catch {
>     // catch handler B
>   } finally {
>     // finally handler C
>   }

In this case you'd need to run finally handler C before catch handler B and
that would be backwards.

lupus

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