On Thursday, 4. September 2008 03:39:20 Larry Wall wrote:
> Another potential issue is that CATCH doesn't distinguish exceptions
> coming from the current block from those coming from the subcall to a().
> So it could end up returning Failure from the current block when
> you intended to force return of Failure from a().  Not sure what
> to do about that...

I don't understand this issue. I think we have the fact that
*every* operator is at least conceptually dispatched and as
such everything in a block is at least one level down in the
call chain just as a() as a sub call is. This is why a CATCH
block inside the block is so natural to me.

If I understand your intention correctly you want to be able
to force a thrown exception from a() into a returned value
and proceed where this return value is supposed to show up
in the current block, right? The simplest solution that comes
to my mind is some form of goto to that position. Or is that
too inelegant? The point is how the CATCH block knows from
which subordinate scope the exception originates.

   a() proceed: orelse b();
      ... # make $! into return value
      goto proceed;

This kind of needs to know the variable the return value of a()
is stored into. This is easy if orelse is checking $! anyway.
But does it? And is it possible to have labels in the middle
of a line as above?

Regards, TSa.
"The unavoidable price of reliability is simplicity" -- C.A.R. Hoare
"Simplicity does not precede complexity, but follows it." -- A.J. Perlis
1 + 2 + 3 + 4 + ... = -1/12  -- Srinivasa Ramanujan

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