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Ruby Learning: Creating Iterators & Using Enumerable Class

Learn how to add iterator support in Ruby by mixing in the Enumerable class and creating custom methods. Explore processing command-line arguments and working with environments and configurations.

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Ruby Learning: Creating Iterators & Using Enumerable Class

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  1. Grabbag IV - the fourth installment of the Trilogy Learning Ruby - 14

  2. Creating Iterators • Adding iterator support (that is, .each, .collect, .inject, etc., etc.) is easy • Simply mixin the Enumerable class into your class • Use include Enumerable near the top of your class code • Create an each method that makes sense for your class

  3. Ethernet.each class Ethernet include Enumerable def each yield @dest yield @src yield @type_len yield @payload end # of each. ... end # of Ethernet.

  4. Slurping Files string_of_lines = IO::read( "/etc/passwd" ) array_of_lines = IO::readlines( "/etc/passwd" )

  5. Processing Command-line Args # Remember: all arguments are passed in as strings! ARGV.each { |arg| puts arg } option1, option2 = ARGV.collect { |arg| arg } if ARGV.length == 0 fail "Please supply some parameters!" end # of if.

  6. Environments and Configurations ENV.keys.each { |key| print "#{key} -> ", ENV[key], "\n" } ENV.collect() do |key, value| print "#{key} --> #{value} \n" end # of do require 'rbconfig' include Config CONFIG.keys.sort.each do |key| print "#{key} -> ", CONFIG[key], "\n" end # of do.

  7. Where Are My Modules? ruby -e 'puts $:' /usr/local/lib/site_ruby/1.8 /usr/local/lib/site_ruby/1.8/i486-linux /usr/local/lib/site_ruby/1.8/i386-linux /usr/local/lib/site_ruby /usr/lib/ruby/1.8 /usr/lib/ruby/1.8/i486-linux /usr/lib/ruby/1.8/i386-linux .

  8. More ... Ruby So Far Look for ways to do cool stuff with Ruby. For example: • A project proposal for 4th Year: Create a Ruby extension that allows for the manipulation of the Torque Game Engine from within any Ruby program.

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