Hi,
I am writing a parrot code generator back-end to an interpreter for a
long-lost (some would say "dead", but I prefer "hibernating" :-)
programming language: Comal (see http://www.josvisser.nl/opencomal).
Anyway, in the course of my code generation I have run into the
situation where I think I need to either:
- Be able to trap a find_lex failure (efficiently), or
- Be able to search the lexical pads for the occurrence of a lexical
with potentially getting "not found" as a result (I dubbed this
feature "search_lex").
The reason is that in this language I can create new variables at any
place in the control flow, but referring to an unknown variable should
throw an error. Also, once created and stored in the lexical
environment, I want assignments to a variable to always refer to the
same PMC (because of a language feature that allows call by reference).
So, my questions are:
1) Is there an efficient way to trap the failure of a "find_lex"?
2) What about a "search_lex" op that follows the format of
"find_lex" but which stores null in the target PMC register
(Px). To make this really useful an "isnull" comparison operator
would come in handy too...
++Jos.es
--
ek is so lug jy vlieg deur my
sonder jou is ek sonder patroon
"Breyten Breytenbach"
