From: daz <dooby@...10.karoo.co.uk>
Date: 2005-11-09T23:57:15+09:00
Subject: Re: Question about symbols


Matthew Smillie wrote:
>
> Thanks for the replies, and if there are no objections to indulging
> me a little further...
>
> > On Nov 9, 2005, at 10:37, daz wrote:
> >
> > I'll wave my hands (in a completely non-scientific way) at 300..500
> > max.
> > (Table look-up isn't hot.)
>
> Is it really that low?  I thought that since symbols are generated
> for every name in Ruby (aren't they?), the ceiling would be a little
> higher before they started being problematic.
>

I'm saying that a typical advantage to using :symbols is in code
that creates them using the literal syntax (:name) in contrast to
'name'.to_sym (formerly 'name'.intern) e.g.:

  cust = {:name => 'Acme', :location => 'some locn', :phone => 'nn-nnn',
          :joindate => Date.new('yy-mm-dd')}
  cust[:lastupdate] = Date.new('today') if custname == cust[:name]
  if cust[:lastupdate] > ...
    custlist[:lastupdate] << cust[:name]
  end

i.e. repeating use of keys/tags within code; same key name
into multiple hashes/structs etc.

I believe that typing :name in a script is the only way
to create a symbol without it having been a ruby String, first.

Once you've typed 300 unique :symbols, you've probably
reached 6000+ lines of code (?)

I don't see any advantage to having nK unique :symbols
over nK unique 'strings'.
(That doesn't imply there isn't one. :)


daz


<st.c>
/* This is a public domain general purpose hash table package
             written by Peter Moore @ UCB. */
/* static char sccsid[] = "@(#) st.c 5.1 89/12/14 Crucible"; */
[...]
</st.c>