Pre-Filled Prompt in Ruby [duplicate]

Answer 1

Maybe googlers will find this useful.

With plain Readline on Ruby 2.1 you could use:

def ask(prompt, default=nil)

  if default
    Readline.pre_input_hook = -> {
      Readline.insert_text(default)
      Readline.redisplay
      # prevent re-trigger on every `readline`
      Readline.pre_input_hook = nil
    }
  end
  data = Readline.readline("#{prompt}: ")
  return data.chomp
end

ask("MOAR...?", "COMPUTARS!") # displays: MOAR...? COMPUTARS!

At the prompt the text COMPUTARS! will be editable

Answer 2

You can do it with RbReadline:

require 'rubygems'
require 'rb-readline'

module RbReadline
  def self.prefill_prompt(str)
    @rl_prefill = str
    @rl_startup_hook = :rl_prefill_hook
  end

  def self.rl_prefill_hook
    rl_insert_text @rl_prefill if @rl_prefill
    @rl_startup_hook = nil
  end
end

RbReadline.prefill_prompt("Previous query")
str = Readline.readline("Enter query: ", true)

puts "You entered: #{str}"