[REBOL] Re: let's re-visit math oper. in a var.
From: gregg:pointillistic at: 3-Apr-2009 14:54
Hi Duke,
mgc> Anyway, I'm also studying (and liking) an old "database" language
mgc> called Mumps or "M" - heavily used in the Healthcare and financial
mgc> circles. That little "calculator routine" that I was using as a
mgc> "sandbox" took me 10 minutes to write properly in Mumps, including
mgc> error trapping. Just another tool in my toolbelt...
What does the result look like in M (is it Cache' or something else
you're using)? Earlier I asked about what you expected it to work
like, because that's one of the things that trips people up when they
come to REBOL from other languages.
In other languages that support an eval concept, there is code, and
you can build up strings and call "eval" on them, interpreting them as
code. The equivalent in REBOL is DO, but there is much more
flexibility in REBOL. DOing strings is rare. You are much better off
building up blocks. The hard part here, with your example, is that
user input is going to start out as strings and you need to convert it
to REBOL types. And what you might normally do in REBOL, for a problem
like this, is build up the input and use PARSE, but I don't usually
throw that at newcomers as an answer, because it's "overload time" if
you're just getting started with REBOL.
I think the biggest <click> in my head was when I finally understood
that there is no code in REBOL, there is only data that is evaluated.
-- Gregg
