[REBOL] Re: Help me, Obi Reb Kenobi, you're my only hope!
From: g:santilli:tiscalinet:it at: 2-Sep-2002 0:39
On Sunday, September 1, 2002, 8:28:22 PM, you wrote:
LM> It looks to me, that the "first class error" and the "legal vs. illegal
LM> error" distinction are two sides of the same coin.
Indeed. We cannot use errors at all, only disarm them. So,
probably we can state that errors can never be "legal", if we
decide that we should never intentionally return an (armed) error.
(It can be seen as a sort of workaround...)
LM> Your IS-REALLY-ERROR? function works for simple code like above, but, AFAIK,
LM> we cannot handle all possible cases, like e.g.:
The problem is that if you enclose the code in a block or a paren
the error is immediately fired; i.e. the only way to return an
error from an expression is if the expression is being evaluated
directly as an argument for a function. This makes me think that
it's likely that this was added as a way to make functions like
DISARM and ERROR? work, but otherwise error!s were intended as a
very special class of values.
I am more and more tempted to start writing a REBOL
implementation, just to try out different approaches and to better
understand why things have been done this way... pity I don't
really have the time to do it.
Gabriele Santilli <[g--santilli--tiscalinet--it]> -- REBOL Programmer
Amigan -- AGI L'Aquila -- REB: http://web.tiscali.it/rebol/index.r