Ruby の自己代入 x ||= 1 未定義
$ irb
2.2-head :001 > x=nil
=> nil
2.2-head :002 > x ||=3
=> 3
2.2-head :003 > x=1
=> 1
2.2-head :004 > x ||=3
=> 1
2.2-head :005 > x
=> 1
$ irb
2.2-head :001 > x=nil
=> nil
2.2-head :002 > x ||=3
=> 3
2.2-head :003 > x=1
=> 1
2.2-head :004 > x ||=3
=> 1
2.2-head :005 > x
=> 1