From: Michael Neumann <mneumann@...>
Date: 2004-10-15T00:53:37+09:00
Subject: [RCR] digest/from_io

Hi,

Would be nice to have in standard Ruby, as it's common to calculate a
digest of a file.

Example of usage:
   
  require 'digest/sha1'
  require 'digest/from_io'

  File.open('/tmp/x') {|f| 
    Digest::SHA1.from_io(f)
  }

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 addition would be the raw_digest method (which of course could
be better implemented in C):

  require 'enumerator'
  class Digest::Base
    def raw_digest
      hexdigest.to_enum(:scan, /../).map {|byte| byte.to_i(16).chr}.join
    end
    alias rawdigest raw_digest
  end

Gavin, feel free to add it to extlib/addlib if you think it's worth.

matz, do you think, we can add from_io to stdlib?

Regards,

  Michael