What am I doing wrong?

[jeryst]

I am trying to create a program that will execute one of several commands, depending on which one I enter, but it's not working. Here is an extremely simple print example that I am using for illustration purposes only. I know that I can print another way, I am just using this as an example. I don't want to use hashs or arrays because some of the commands may be quite lengthy.

#***************************************
def dog
puts 'I am a dog.'
end

def cat
puts 'I am a cat.'
end

puts 'Enter command: '
command_in = gets.chomp.downcase
command_in
puts 'Command ' + command_in + " executed.'
#***************************************

Here is what my output looks like...

Enter command:
(I enter "dog" as the response)
Command dog executed.

Here is what I want my output to look like...

Enter command:
(I enter "dog" as the response)
I am a dog.
Command dog executed.


How can I get the program to actually do command_in instead of treating it as a literal? I think I may have to create a proc or something, but I don't know how to do it.

[IAIHMB]

There has to be a better way to do it, but you could use eval so long as you validate the input:

http://pastie.caboo.se/12374

[Luke Redpath]

Please try and use code blocks when posting code.

Easiest way would be the following:

module Commands
  def self.dog
    puts 'I am a dog.'
  end

  def self.cat
    puts 'I am a cat.'
  end
end

puts 'Enter command: '
command_in = gets.chomp.downcase
Commands.send(command_in)
puts 'Command ' + command_in + " executed.'

It has to be said though, allowing users to arbitrarily call methods is somewhat of a security hole. Always remember to validate input.

[IAIHMB]

Luke beat me to it, I just remembered send and that all methods are a part of a class, similarly:

def cat; puts "Cat!"; end

def dog; puts "Dog!"; end

puts "Enter a method to execute:"
desired_method = gets.downcase.chomp
Object.send(desired_method)
puts "Executed #{desired_method}."

[jeryst]

Thanks guys. This is all still very confusing to me, as I am an old school COBOL programmer, and have no experience at all in these types of languages. I think it's going to be twice as hard for me, because not only do I need to learn a lot of new habits and conventions, but I need to unlearn old habits and conventions as well. I can see that this stuff requires a different type of thinking. I hope you can put up with me as I continue to ask questions.

[Luke Redpath]

Luke beat me to it, I just remembered send and that all methods are a part of a class, similarly:

def cat; puts "Cat!"; end

def dog; puts "Dog!"; end

puts "Enter a method to execute:"
desired_method = gets.downcase.chomp
Object.send(desired_method)
puts "Executed #{desired_method}."

Its worth mentioning that this is even more insecure than my method