Original Prototype Rake

This is the original 100 line prototype rake program.

#!/usr/bin/env ruby

require 'ftools'

class Task
  TASKS = Hash.new

  attr_reader :prerequisites

  def initialize(task_name)
    @name = task_name
    @prerequisites = []
    @actions = []
  end

  def enhance(deps=nil, &block)
    @prerequisites |= deps if deps
    @actions << block if block_given?
    self
  end

  def name
    @name.to_s
  end

  def invoke
    @prerequisites.each { |n| Task[n].invoke }
    execute if needed?
  end

  def execute
    return if @triggered
    @triggered = true
    @actions.collect { |act| result = act.call(self) }.last
  end

  def needed?
    true
  end

  def timestamp
    Time.now
  end

  class << self
    def [](task_name)
      TASKS[intern(task_name)] or fail "Don't know how to rake #{task_name}"
    end

    def define_task(args, &block)
      case args
      when Hash
	fail "Too Many Target Names: #{args.keys.join(' ')}" if args.size > 1
	fail "No Task Name Given" if args.size < 1
	task_name = args.keys[0]
	deps = args[task_name]
      else
	task_name = args
	deps = []
      end
      deps = deps.collect {|d| intern(d) }
      get(task_name).enhance(deps, &block)
    end

    def get(task_name)
      name = intern(task_name)
      TASKS[name] ||= self.new(name)
    end

    def intern(task_name)
      (Symbol === task_name) ? task_name : task_name.intern
    end
  end
end

class FileTask < Task
  def needed?
    return true unless File.exist?(name)
    latest_prereq = @prerequisites.collect{|n| Task[n].timestamp}.max
    return false if latest_prereq.nil?
    timestamp < latest_prereq
  end

  def timestamp
    File.new(name.to_s).mtime
  end
end

def task(args, &block)
  Task.define_task(args, &block)
end

def file(args, &block)
  FileTask.define_task(args, &block)
end

def sys(cmd)
  puts cmd
  system(cmd) or fail "Command Failed: [#{cmd}]"
end

def rake
  begin
    here = Dir.pwd
    while ! File.exist?("Rakefile")
      Dir.chdir("..")
      fail "No Rakefile found" if Dir.pwd == here
      here = Dir.pwd
    end
    puts "(in #{Dir.pwd})"
    load "./Rakefile"
    ARGV.push("default") if ARGV.size == 0
    ARGV.each { |task_name| Task[task_name].invoke }
  rescue Exception => ex
    puts "rake aborted ... #{ex.message}"
    puts ex.backtrace.find {|str| str =~ /Rakefile/ } || ""
  end
end

if __FILE__ == $0 then
  rake
end