A gist demoing four valid ways to write do…while functionality in Ruby

example.rb

# Which is the most stylistically correct way to emulate a do…while in Ruby?

# option one
begin
	mark = gets.chomp
end unless mark == "A2" # loops again when the mark is A2.

# option two
loop do
	mark = gets.chomp
	break unless mark == "A2"
end

# option three 
1.times do
	mark = gets.chomp
	retry if mark == "A2"
end

# option four – suggested by @radar
while true
	mark = gets.chomp
	break unless mark == "A2"
end

Also discussed on Stack Overflow.