From: Austin Ziegler <halostatue@...>
Date: 2004-10-16T23:14:10+09:00
Subject: Re: [RCR] digest/from_io

On Sat, 16 Oct 2004 19:20:58 +0900, Michael Neumann <mneumann@ntecs.de> wrote:
> On Fri, Oct 15, 2004 at 12:03:17PM +0900, Nobuyoshi Nakada wrote:
> > Hi,
> >
> > At Fri, 15 Oct 2004 00:53:37 +0900,
> > Michael Neumann wrote in [ruby-talk:116637]:
> > > Implementation:
> > >
> > >   # file: digest/from_io.rb
> > >   class Digest::Base
> > >     def self.from_io(io, block_size=8*1024)
> > >       digest = new
> > >       while data = io.read(block_size)
> > >         digest.update(data)
> > >       end
> > >       digest
> > >     end
> > >   end
> >
> > Another implementation could be:
> >
> >   def Digest::Base.from(src)
> >     digest = new
> >     src.each(&digest.method(:update))
> >     digest
> >   end
> >
> > This requires #each method instead of #read, do you think which
> > is better?
> What if #each does not return a string? Does #update work for all Ruby
> objects? Personally I like #from_io more, as it's more natural how it
> works.

#update should work on all Digest::Base subclasses. This line is roughly:

    src.each { |data| digest.update(data) }

Digest#update methods should work with individual bytes or strings,
shouldn't they?

It also depends on what Digest#update does to the implied data value;
if it calls #to_s or #to_str, then arrays of strings or other values
could be dealt with very easily. To me, that would be as or more
useful than limiting it to IO objects; I might want to generate a
digest from the result of IO::readlines (an array of strings).

-austin
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