require 'digest.so' module Digest def self.const_missing(name) case name when :SHA256, :SHA384, :SHA512 lib = 'digest/sha2.so' else lib = File.join('digest', name.to_s.downcase) end begin require lib rescue LoadError => e raise LoadError, "library not found for class Digest::#{name} -- #{lib}", caller(1) end unless Digest.const_defined?(name) raise NameError, "uninitialized constant Digest::#{name}", caller(1) end Digest.const_get(name) end class ::Digest::Class # creates a digest object and reads a given file, _name_. # # p Digest::SHA256.file("X11R6.8.2-src.tar.bz2").hexdigest # # => "f02e3c85572dc9ad7cb77c2a638e3be24cc1b5bea9fdbb0b0299c9668475c534" def self.file(name) new.file(name) end end module Instance # updates the digest with the contents of a given file _name_ and # returns self. def file(name) File.open(name, "rb") {|f| buf = "" while f.read(16384, buf) update buf end } self end end end def Digest(name) Digest.const_get(name) end