Seven Languages in Seven Weeks - Ruby

day2_1.rb

#!/usr/bin/env ruby

# print array in slices using each
a = (1..16).to_a
(0..3).each do |i|
	p a[4*i..4*i+3]
end

# print array in slices using each_slice
a.each_slice(4) {|s| p s}


############################
# Tree initialized by a hash
############################

class Tree
	attr_accessor :children, :node_name

	def initialize(tree, node_name=nil)
		if (node_name.nil? and tree.size == 1)
			first = tree.first
			@node_name = first[0]
			children_hash = first[1]
		elsif (not node_name.nil?)
			@node_name = node_name
			children_hash = tree
		else
			raise ArgumentError
		end
		@children = children_hash.collect {|name, subtree| Tree.new(subtree, name)}
	end

	def visit_all(&block)
		visit &block
		children.each {|c| c.visit_all &block}
	end

	def visit(&block)
		block.call self
	end
end

my_tree = Tree.new({
	'grandpa' => {
		'dad' => {
			'child 1' => {}, 'child 2' => {}
		}, 
		'uncle' => {
			'child 3' => {}, 'child 4' => {}
		}
	}
})

my_tree.visit_all {|node| puts node.node_name}

day2_grep.rb

#!/usr/bin/env ruby

filename = ARGV[0]
phrase = ARGV[1]

if (filename.nil? || phrase.nil?)
	puts "Usage: day2_grep.rb filename phrase"
	exit;
end

File.open(filename, File::RDONLY) do |file|
	file.each_with_index { |line, nr| puts "Line " + (nr+1).to_s.rjust(4) + ": " + line if line =~ /#{phrase}/ }
end

day3.rb

class CsvRow
	def initialize(headers, row)
		@headers = headers
		@row = row
	end

	def method_missing(name, *args)
		idx = headers.index(name.to_s)
		raise NoMethodError if idx.nil?
		row[idx]
	end

	def headers
		@headers
	end

	def row
		@row
	end
end

module ActsAsCsv

	def self.included(base)
		base.extend ClassMethods
	end

	module ClassMethods
		def acts_as_csv
			include InstanceMethods
		end
	end

	module InstanceMethods

		define_method 'read' do
			file = File.new(self.class.to_s.downcase + '.txt')
			@headers = file.gets.chomp.split(', ')

			file.each do |row|
				@result << row.chomp.split(', ')
			end
		end

		define_method "headers" do
			@headers
		end

		define_method "csv_contents" do
			@result
		end

		define_method "initialize" do
			@result = []
			read
		end

		define_method "each" do |*args, &block|
			csv_contents.each {|row| block.call CsvRow.new(headers, row)}
		end

	end
end

class RubyCsv
	include ActsAsCsv
	acts_as_csv
end

m = RubyCsv.new
m.each {|row| puts row.header1}

# rubycsv.txt:
# header1, header2
# row1_col1, row1_col2
# row2_col1, row2_col2