Ruby - Block Return Values: How Should I Handl This?(Opening the file、Safely closing the file, with a block、Don't forget about variable scope!)

Head First Ruby

開発環境

• OS X El Capitan - Apple (OS)
• Emacs (Text Editor)
• Ruby 2.3 (プログラミング言語)

Head First Ruby (Jay McGavren (著)、O'Reilly Media)のChapter 6.(Block Return Values: How Should I Handl This?)、Opening the file、Safely closing the file, with a block、Don't forget about variable scope!、EXERCISE(No. 3516)を取り組んでみる。

EXERCISE(No. 3516)

コード(Emacs)

#!/usr/bin/env ruby2.3
# -*- coding: utf-8 -*-

def yield_number
  yield 4
end

array = [1, 2, 3]
yield_number { |number| array << number }

p array

sum = 0
[1, 2, 3].each { |number| sum += number}
puts sum

contents = []
File.open("sample.txt") do |file|
  contents = file.readlines
end

puts contents
                                 

入出力結果(Terminal)

$ ./sample1.rb 
[1, 2, 3, 4]
6
This is the first line in the file.
This is the second.
this is the last line.
$