How to make two Ruby programs communicate with each other-CodePudding

I have a simple program 'guessing game' written in Ruby. It asks for a 1-100 number and returns if the number you're guessing is higher or lower. Now I have to create a second program that can play that game optimally. What would be the best way to make them communicate with each other? I can also use bash script.

CodePudding user response：

It's an excellent idea to use bash for this exercise, because you can test each program individually using the shell, and then later easily connect the two also using the shell.

Simply read from stdin as the input of a program, write the result to stdout. Write to stderr to log program behavior.

As a starting point, here is a program that checks the guessed number:

$ cat ./check_guess.rb
#!/usr/bin/ruby

# Ensure output is flushed when piping
STDOUT.sync = true

# Reference number, could be provided by the user or randomly generated, etc.
ref = 12

while true

  # Get input
  guess = gets
  if guess.to_s != ""

    STDERR.puts "Received guess = "   guess

    # Compare with ref. number
    if guess.to_i > ref 
      STDERR.puts "Provided number is higher than "   ref.to_s
      puts "higher"
    elsif guess.to_i < ref 
      STDERR.puts "Provided number is lower than "   ref.to_s
      puts "lower"
    else
      STDERR.puts "Provided number matches!"
      puts "match"  if ref == guess.to_i
      break
    end 
  end 
end

Testing it manually:

$ ./check_guess.rb 
10  
Received guess = 10
Provided number is lower than 12
lower
13  
Received guess = 13
Provided number is higher than 12
higher
12  
Received guess = 12
Provided number matches!
match

Here a very crude guessing program:

$ cat guess.rb 
#!/usr/bin/ruby

# Ensure output is flushed when piping
STDOUT.sync = true

# Initial guess. Could be provided by the user or randomly generated, etc.
guess = 5 

# Loop until we guess correctly
while true

  # Provide guess by simply writing to stdout
  STDERR.puts "Guessing number is "   guess.to_s

  # Print current guess
  puts guess.to_s

  # Get guess result from stdin, that is, from the other program...
  # Use chomp to remove the newline
  result = gets.chomp

  if result == "match"
    STDERR.puts "Guessed!"
    break
  elsif result == "higher"
    guess = guess - 1 
    STDERR.puts "Provided number is higher, trying smaller number"
  else
    guess = guess   1 
    STDERR.puts "Provided number is smaller, trying higher number"
  end 
end

This can also be tested manually:

$ ./guess.rb 
Guessing number is 5
5   
higher
Provided number is higher, trying smaller number
Guessing number is 4
4   
match
Guessed!

Now, let's create pipes to connect the programs with each other:

$ mkfifo guess_out check_guess_out

And run them from two terminals. Note that the stderr messages will still go to the terminal, the commands below just connect stdout from one program to the stdin of the other.

$ cat check_guess_out | ./guess.rb > ./guess_out  | $ cat guess_out | ./check_guess.rb > check_guess_out 
Guessing number is 5                              | Received guess = 5 
Provided number is smaller, trying higher number  | Provided number is lower than 12
Guessing number is 6                              | Received guess = 6 
Provided number is smaller, trying higher number  | Provided number is lower than 12
Guessing number is 7                              | Received guess = 7 
Provided number is smaller, trying higher number  | Provided number is lower than 12
Guessing number is 8                              | Received guess = 8 
Provided number is smaller, trying higher number  | Provided number is lower than 12
Guessing number is 9                              | Received guess = 9 
Provided number is smaller, trying higher number  | Provided number is lower than 12
Guessing number is 10                             | Received guess = 10
Provided number is smaller, trying higher number  | Provided number is lower than 12
Guessing number is 11                             | Received guess = 11
Provided number is smaller, trying higher number  | Provided number is lower than 12
Guessing number is 12                             | Received guess = 12
Guessed!                                          | Provided number matches!

Now follows the real interesting part, which is to devise a guessing algorithm. Good luck!