From: "Ara.T.Howard" <ahoward@...>
Date: 2004-04-24T00:14:11+09:00
Subject: Re: find a best version (of a package)

On Fri, 23 Apr 2004, Kristof Bastiaensen wrote:

> On Fri, 23 Apr 2004 21:17:14 +0900, saiph wrote:
> 
> > 
> > hi list,
> > 
> > 
> > i'm following the "learning ruby" path, i've found this list very usefull the 
> > last time (tnx), so i thought to send this simple example to better 
> > understand what'd to be a good programming style.
> > 
> > 
> > 
> > alea> expand -t 2 best_vv
> > -----------------------------------------------
> > class String
> > def newer?(s)
> >   b = self.dup
> > 
> >   b.sub!(/(\w+-)/, '')
> >   t = $+
> >   s.sub!(/(\w+-)/, '')
> > 
> >   return -1 if t != $+  # not the same package
> > 
> >   while (b.sub!(/(\d+\.|\d+)/, '')) do
> >     t = $+.chomp('.')
> >     s.sub!(/(\d+\.|\d+)/, '')
> > 
> >     return 1 if $+ == nil
> >     return 1 if t.to_i > $+.chomp('.').to_i
> >   end
> > 
> >   return 0
> > end
> > end
> > 
> > class Array
> > def best_version?
> >   s = 0
> > 
> >   for i in 1..self.length() - 1 do
> >     t = self[i].newer? self[s]
> >     if t == 1
> >       s = i
> >     elsif t == -1
> >       return nil
> >     end
> >   end
> > 
> >   return s
> > end
> > end
> > 
> > vv = ['ruby-2.2.5', 'ruby-3.2.6', 'ruby-5']
> > i = vv.best_version?
> > puts vv[i]
> > -----------------------------------------------
> > 
> > how would you write or change this?
> > 
> > 
> > tnx again for your time :)
> > 
> > best regards,
> > saiph
> 
> My try:
> 
> r = /ruby-([\d.]+)/
> ['ruby-2.2.5', 'ruby-3.2.6', 'ruby-5'].max { |a, b|
>   r.match(a)[1].split(".") <=> r.match(b)[1].split(".") }
> 
> or shorter:
> 
> ['ruby-2.2.5', 'ruby-3.2.6', 'ruby-5'].sort_by { |s|
>   /ruby-([\d.]+)/.match(s)[1].split(".") }[-1]
> 
> (I am not sure which one performs the best).
> 
> My opinion about programming style is:  make things as
> simple as you can.  Don't create extra helper classes
> etc if you don't need them.
> 
> Kristof
> 


i think the problem with both these approaches are that they may not reflect
the semantics of version numbers!  for instance, i use the linux/libtool style
of versioning (the same used by ld.so - man ld.so)

see

  http://raa.ruby-lang.org/list.rhtml?name=library

specifically

  http://www.codeforpeople.com//lib/ruby/library/library-0.0.0/doc/

so

  if my code requires version 2.1.5, i could use 7.5.0 but NOT 3.0.4

-a
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