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Jason Woo
11,730 PointsHi there I redid the contact_list project on my own and cannot diagnose this issue. Could you tell me what's wrong?
def ask(question, type = "string") puts question + " " answer = gets.chomp if type == 'number' answer = answer.to_i end return answer end
contact_list = []
def add_contact contact = {'name' => '', 'phone_numbers' => []} contact['name'] = ask('What is the name of the contact? ') add_number ="" until add_number == 'n' add_number = ask("Add a number for #{contact['name']}? (y/n)") if add_number == 'y' contact['phone_numbers'].push(ask('Enter a number for ' + contact['name'])) end end return contact end
def show contact_list.each do |contacts| puts "Name: #{contacts['name']}" contacts['phone_numbers'].each do |numbers| puts "Number: #{numbers}" end puts "------------ \n" end end
answer = "" until answer == 'n' contact_list.push(add_contact) answer = ask('Would you like to add another contact? (y/n)') end
show
4 Answers
Brendan Whiting
Front End Web Development Techdegree Graduate 84,735 PointsI ran your code and I got this error when I got to the end:
contact_list.rb:26:in `show': undefined local variable or method `contact_list' for main:Object (NameError)
from contact_list.rb:41:in `<main>'
Is that the problem you're referring to? If so, this seems to be a problem with variable scope. This stack overflow answer was enlightening: https://stackoverflow.com/questions/9671259/ruby-local-variable-is-undefined
I applied this to "define method" change to your code and it solve that error, see line line 26 in the code below:
def ask(question, type = "string")
puts question + " "
answer = gets.chomp
if type == 'number'
answer = answer.to_i
end
return answer
end
contact_list = []
def add_contact
contact = {'name' => '', 'phone_numbers' => []}
contact['name'] = ask('What is the name of the contact? ')
add_number =""
until add_number == 'n'
add_number = ask("Add a number for #{contact['name']}? (y/n)")
if add_number == 'y'
contact['phone_numbers'].push(ask('Enter a number for ' + contact['name']))
end
end
return contact
end
define_method :show do
contact_list.each do |contacts|
puts "Name: #{contacts['name']}"
contacts['phone_numbers'].each do |numbers|
puts "Number: #{numbers}"
end
puts "------------ \n"
end
end
answer = ""
until answer == 'n'
contact_list.push(add_contact)
answer = ask('Would you like to add another contact? (y/n)')
end
show
Jason Woo
11,730 PointsYes, I received the same error.
I don't understand why contact_list is unavailable when I already defined it in the outermost scope (aka local variable correct?). My previous understanding was that methods and classes should be able to access them.
Based on what I read in your link, my new understanding is methods (written as def or class) can only access variables defined within themselves, whereas classes can access outermost/local variables. Is that right?
Your edit on line 26 allows for the method to take from local variables (like classes), and can be called upon like a normal method without the :(colon). Correct?
Brendan Whiting
Front End Web Development Techdegree Graduate 84,735 PointsHonestly, it surprised me too. I'm more of a JavaScript guy, so my understanding of scope is from that language, and this isn't how I expected it to behave. But I guess that's ruby.
Jason Woo
11,730 PointsI also want to make sure I have the syntax of define_method nailed down.
1) The colon is necessary (I tried it without and ran an error when called) 2) Requires the word 'do', unlike a regular method definition. 3)In order to call the method, it has to be without the colon (so its show, not :show in our case).
Brendan Whiting
Front End Web Development Techdegree Graduate 84,735 PointsI'm sorry I can't speak with very much authority about Ruby syntax.
Jason Woo
11,730 PointsNo worries, those were just the conclusions I came to from experimenting.
Thank you so much for help!