errors in deaf Grandma - Pine - No Method

问题

Was completing the pine exercise for Def Grandma and thought would try and take it a little further and abstract it to remove as much duplication as possible.

Hope my logic with this isn't too bizzare just tried to separate things into functions. But now if I type

Bye

The program exits immediately without proceeding to the exitPlan function. Any advice welcome.

puts 'Say something nice to Grandma.'
puts 'You may need to shout > '
speak = gets.strip
counter = 0
speaks(speak)

def speaks(speak)
    if speak != 'Bye'
        talk()
    else
        exitPlan()
    end
end

def talk()
    if speak == speak.downcase
        puts 'Huh Speak up Sonny'
        counter -= 1 
    else
        year = rand(1930..1951)
        puts 'No not Since ' + year.to_s
        counter -= 1
    end
        if counter < 0 
            counter = 0 # don't want counter going below zero.
            end
        puts 'Say something nice to Grandma'
        speaks()
end

def exitPlan()
    counter += 1
    unless counter == 3
        puts 'Say something nice to Grandma'
        speaks()
    else
        puts 'good night Sonny'
    end
end

Error

renshaw@renshaw-TravelMate-5740G:~/Ruby$ ruby -W dGrand.rb 
Say something nice to Grandma.
You may need to shout > 
Bye
dGrand.rb:6:in `<main>': undefined method `speaks' for main:Object (NoMethodError)
renshaw@renshaw-TravelMate-5740G:~/Ruby$

回答1:

You need to move the lines

puts 'Say something nice to Grandma.'
puts 'You may need to shout > '
speak = gets.strip
counter = 0
speaks(speak)

to after your method definition so that the speaks method has been defined when you reach the speaks(speak) line.

Then next problem you will probably encounter is

in `exitPlan': undefined method `+' for nil:NilClass

This is because counter is a local variable so is not shared between your toplevel code and the different methods. You will need to either use a global variable i.e. $counter for this or, better, put the various methods inside a class and then use an instance variable.

I suspect there are still some other issues in your code such as you only seem to be calling gets.strip to get the input once. However, in terms of wrapping the code inside a class it's not the counter that you want to wrap as you would still need to pass that around between the various methods. It's the whole speak/talk interaction so something along the lines of

class Grandma
  def initialize
    @counter = 0
  end

  def speaks(speak)
    ..
  end

  def talk()
    ..
  end

  def exitPlan()
    ..
  end
end

grandma = Grandma.new
grandma.speaks(speak)

and substitute the places where you're currently using the local counter variable with references to @counter

回答2:

You are calling method speaks before it's defined. See Ruby: How to call function before it is defined?

回答3:

Look at the other posts explaining the use of methods and globals. Here you have a gist that works with Ruby 1.9.3 because of how you used rand

来源：https://stackoverflow.com/questions/9095047/errors-in-deaf-grandma-pine-no-method

标签

ruby

function

ruby-1.9