On Sep 20, 2008, at 1:39 PM, Brice Figureau wrote:
>
> Hi,
>
> The more I think about that patch, the more I think I should expand it
> to a more generic expression parser/evaluator by adding arithmetic
> operators and such, so that we could write these stupid things:
>
> class superfeaturethatneedsplentyofram {
> $min_ram = 2048 * 1024 * 1024
> if ($ram / (1024*1024) < $min_ram) {
> notice("not enough ram on node ${fqdn}")
> }
> }
>
> I already started coding this in fact and I'm wondering if that's
> something that:
> * is needed (I never myself got the need)
> * would be welcome
>
> Anyway, that's an interesting exercise (mainly due to the lack or racc
> documentation or examples). Right now I'm struggling with shift/reduce
> conflicts I don't really know how to solve (anyone familiar with LALR
> parsers lurking here, please I welcome any help :-)).
Note that Puppet's language doesn't have numbers -- they're all
treated as strings (only 'true' and 'false', when unquoted, are
anything but strings) -- so you'll have to do a touch of magic to make
math work.
Generally, I'm not opposed to this but I don't think it's all that
important, either. I expect others will stauchly disagree with me,
though, and would love this functionality.
The lack of racc documentation is quite fun -- I can only ever find my
own threads and code when looking for it. I can't imagine I'm the only
person to ever use it, but I might be the only one to ever publish
anything using it.
In terms of shift/reduce conflicts, they are the bane of LALR parser
generators. I'm willing to do what I can to help, but they're pretty
unfun. What's your code look like right now?
BTW, one thing that might be useful is to create a stand-alone parser
that just does the arithmetic, and when you're happy with it, import
it into Puppet. Then again, that might be 10x harder. :)
--
I can win an argument on any topic, against any opponent. People know
this, and steer clear of me at parties. Often, as a sign of their
great respect, they don't even invite me. -- Dave Barry
---------------------------------------------------------------------
Luke Kanies | http://reductivelabs.com | http://madstop.com
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