From: Robert Klemme <bob.news@...>
Date: 2004-04-23T16:09:04+09:00
Subject: Re: parsing memory specs


"Robert Klemme" <bob.news@gmx.net> schrieb im Newsbeitrag
news:c6ad9d$9q96m$1@ID-52924.news.uni-berlin.de...
>
> "Ara.T.Howard" <Ara.T.Howard@noaa.gov> schrieb im Newsbeitrag
> news:Pine.LNX.4.44.0404222216280.8026-100000@fattire.ngdc.noaa.gov...
> >
> > i don't know how many times i've written this...
> >
> >   spec = '2000GB'
> >
> >   size =
> >     case spec
> >       when /gb\s*$/io
> >         spec.to_i * (2 ** 30)
> >       when /mb\s*$/io
> >         spec.to_i * (2 ** 20)
> >       when /kb\s*$/io
> >         spec.to_i * (2 ** 10)
> >       else
> >         spec.to_i
> >     end
> >
> > is there anything which parses memory specs anywhere in the stdlib?
>
> If not, why don't you put it into a file and store that in ~/lib/ruby?
>
> Btw. personally I would choose a different implementation.
>
> def parse_mem_size(spec)
>   m = /^(\d+) ?(?:([kmgt])b)?$/i.match( spec ) or
>     raise ArgumentError, "Illegal mem spec '#{spec}'"
>
>   m[1].to_i * case m[2].downcase[0]
>     when ?k; 1024
>     when ?m; 1048576
>     when ?g; 1073741824
>     when ?t; 1099511627776
>     else     1
>   end
> end

This should have read

def parse_mem_size(spec)
  m = /^(\d+) ?(?:([kmgt])b)?$/i.match( spec ) or
    raise ArgumentError, "Illegal mem spec '#{spec}'"

  m[1].to_i * case m[2] && m[2].downcase[0]
    when ?k; 1024
    when ?m; 1048576
    when ?g; 1073741824
    when ?t; 1099511627776
    else     1
  end
end

A solution involving a hash for the factors is probably even faster.

Cheers

    robert