Ruby: gets.chomp with default value - ruby

Question

Is there some simple way how to ask for a user input in Ruby WHILE providing a default value?
Consider this code in bash:
function ask_q {
local PROMPT="$1"
local DEF_V="$2"
read -e -p "$PROMPT" -i "$DEF_V" REPLY
echo $REPLY
}
TEST=$(ask_q "Are you hungry?" "Yes")
echo "Answer was \"$TEST\"."
Can you achieve similar behaviour with Ruby's gets.chomp?
function ask_q(prompt, default="")
puts prompt
reply = gets.chomp() # ???
return reply
def
reply = ask_q("Are you hungry?", "Yes")
I understand I can sort replicate the functionality in Ruby this way ...
def ask_q(prompt, default="")
default_msg = (default.to_s.empty?) ? "" : "[default: \"#{default}\"]"
puts "${prompt} ${default}"
reply = gets.chomp()
reply = (default.to_s.empty?) ? default : reply
return reply
end
... but it does not seem very pretty. I also need to show the default value manually and the user needs to retype it in the prompt line, if he wants to use modified version of it (say yes! instead of yes).
I'm starting with Ruby now, so there may be a lot of syntax mistakes and I also may be missing something obvious ... Also, I googled a lot but surprisingly found no clue.
TL; DR
To make the question clearer, this is what you should see in terminal and what I am able to achieve in bash (and not in Ruby, so far):
### Terminal output of `reply=ask_q("Are you hungry?" "Yes")`
$ Are you hungry?
$ Yes # default editable value
### Terminal output of `reply=ask_q("What do you want to eat?")`
$ What do you want to eat?
$ # blank line waiting for user input, since there is no second parameter
And the actual situation: I am building bootstrap script for my web apps. I need to provide users with existing configuration data, that they can change if needed.
### Terminal output of `reply=ask_q("Define name of database." "CURR_DB_NAME")`
I don't think it's that fancy functionality, that would require switch to GUI app world.
And as I've said before, this is quite easily achievable in bash. Problem is, that other things are pure pain (associative arrays, no return values from functions, passing parameters, ...). I guess I just need to decide what sucks the least in my case ...

Answer 1

You need to do one of two things:
1) Create a gui program.
2) Use curses.
Personally, I think it's a waste of time to spend any time learning curses. Curses has even been removed from the Ruby Standard Library.
A GUI program:
Here is what a gui app looks like using the Tkinter GUI Framework:
def ask_q(prompt, default="")
require 'tk'
root = TkRoot.new
root.title = "Your Info"
#Display the prompt:
TkLabel.new(root) do
text "#{prompt}: "
pack("side" => "left")
end
#Create a textbox that displays the default value:
results_var = TkVariable.new
results_var.value = default
TkEntry.new(root) do
textvariable results_var
pack("side" => "left")
end
user_input = nil
#Create a button for the user to click to send the input to your program:
TkButton.new(root) do
text "OK"
command(Proc.new do
user_input = results_var.value
root.destroy
end)
pack("side" => "right", "padx"=> "50", "pady"=> "10")
end
Tk.mainloop
user_input
end
puts ask_q("What is your name", "Petr Cibulka")
Calling a function in a bash script from ruby:
.../bash_programs/ask_q.sh:
#!/usr/bin/env bash
function ask_q {
local QUESTION="$1"
local DEFAULT_ANSWER="$2"
local PROMPT="$QUESTION"
read -p "$PROMPT $DEFAULT_ANSWER" USERS_ANSWER #I left out the -i stuff, because it doesn't work for my version of bash
echo $USERS_ANSWER
}
ruby_prog.rb:
answer = %x{
source ../bash_programs/ask_q.sh; #When ask_q.sh is not in a directory in your $PATH, this allows the file to be seen.
ask_q 'Are you Hungry?' 'Yes' #Now you can call functions defined inside ask_q.sh
}
p answer.chomp #=> "Maybe"
Using curses:
require 'rbcurse/core/util/app'
def help_text
<<-eos
Enter as much help text
here as you want
eos
end
user_answer = "error"
App.new do #Ctrl+Q to terminate curses, or F10(some terminals don't process function keys)
#form.help_manager.help_text = help_text() #User can hit F1 to get help text (some terminals do not process function keys)
question = "Are You Hungry?"
default_answer = "Yes"
row_position = 1
column_position = 10
text_field = Field.new(#form).
name("textfield1").
label(question).
text(default_answer).
display_length(20).
bgcolor(:white).
color(:black).
row(row_position).
col(column_position)
text_field.cursor_end
text_field.bind_key(13, 'return') do
user_answer = text_field.text
throw :close
end
end
puts user_answer