class Deck
attr_accessor :all
def initialize
#all = [1,2,3]
end
end
newdeck = Deck.new
puts newdeck.all
class Testdeck
attr_accessor :cards
def initialize
#cards = []
counter = 0
['H','C', 'S', 'D'].product(['2','3','4','5','6','7','8','9','10','J','K','Q','A']).each do |arr|
#cards << Card.new(arr[0], arr[1])
end
end
end
zen = Testdeck.new
puts zen.cards.pop
This code is giving me: 'block in initialize' uninitialized constant Testdeck NameError
All help is appreciated.
This code has no clue what a Card is; the error message you're getting is not an uninitialized constant Testdeck error but an uninitialized constant Testdeck::Card error, where the :: indicates that Ruby is looking inside the Testdeck class for the Card class (not that you need to put it there, Ruby just looks there first).
You need to define the Card class somewhere, and make its constructor take in a string and an integer.
Related
I've redone the question and included the full code for both files. In the touch_in method I am trying to instantiate a Journey class in the variable called 'journey'.
require_relative 'journey'
class Oystercard
MAXIMUM_BALANCE = 90
MINIMUM_BALANCE = 1
MINIMUM_CHARGE = 1
def initialize
#balance = 0
#journeys = {}
end
def top_up(amount)
fail 'Maximum balance of #{maximum_balance} exceeded' if amount + balance > MAXIMUM_BALANCE
#balance += amount
end
def in_journey?
#in_journey
end
def touch_out(station)
deduct(MINIMUM_CHARGE)
#exit_station = station
#in_journey = false
#journeys.merge!(entry_station => exit_station)
end
def touch_in(station)
fail "Insufficient balance to touch in" if balance < MINIMUM_BALANCE
journey = Journey.new
#in_journey = true
#entry_station = station
end
attr_reader :journeys
attr_reader :balance
attr_reader :entry_station
attr_reader :exit_station
private
def deduct(amount)
#balance -= amount
end
end
The Journey file is as follows:
class Journey
PENALTY_FARE = 6
MINIMUM_CHARGE = 1
def initialize(station = "No entry station")
#previous_journeys = {}
end
def active?
#active
end
def begin(station = "No entry station")
#active = true
#fare = PENALTY_FARE
#entry_station = station
end
def finish(station = "No exit station")
#active = false
#fare = MINIMUM_CHARGE
#exit_station = station
#previous_journeys.merge!(entry_station => exit_station)
end
attr_reader :fare
attr_reader :previous_journeys
attr_reader :entry_station
attr_reader :exit_station
end
I think that the 'touch_in' method should create a 'journey' variable that I called methods on, such as 'finish(station)' or 'active?' etc. When I attempt to do this in IRB I am given the following error:
2.6.3 :007 > journey
Traceback (most recent call last):
4: from /Users/jamesmac/.rvm/rubies/ruby-2.6.3/bin/irb:23:in `<main>'
3: from /Users/jamesmac/.rvm/rubies/ruby-2.6.3/bin/irb:23:in `load'
2: from /Users/jamesmac/.rvm/rubies/ruby-2.6.3/lib/ruby/gems/2.6.0/gems/irb-1.0.0/exe/irb:11:in `<top (required)>'
1: from (irb):7
NameError (undefined local variable or method `journey' for main:Object)
I'm aware that much of the code above is sloppily written and there are probably other bits, beside the 'journey' issue, where it's just incorrect. Please let me know if this is the case, the more I'm told the better.
Apologies to anyone who attempted to help me on my first attempt, as I say I'm still getting used to SO and was trying to make the post easier to read.
class Journey
# ...
def initialize
puts "Journey initialized"
# ...
end
# ...
end
require_relative 'journey'
class Oystercard
def initialize
end
# ...
def touch_in(station)
journey = Journey.new
# ...
end
end
Oystercard.new.touch_in("station")
stack_question$ ruby oystercard.rb
Journey initialized
It works fine - are you having some issue with this that is beyond the scope of the question?
I am ruby beginner. I am use proc class but I am getting error.
class Timeline
attr_accessor :tweets
def each(&block) # Block into the proc
tweets.each(&block) # proc back into the block
end
end
timeline = Timeline.new(tweets)
timeline.each do |tweet|
puts tweet
end
Getting error :-
`each': undefined method `each' for nil:NilClass (NoMethodError)
How to solve this error? Please tell us!
When you define attr_accessor :tweets, you just define 2 instance methods:
def tweets
#tweets
end
def tweets=(tweets)
#tweets = tweets
end
When you call tweets inside the each method, you just call method with this name, not a local variable, so you should set #tweets in the initialize method because right now your #tweets variable is not set:
class Timeline
attr_accessor :tweets # this is just a nice syntax for instance variable setter
# and getter
def initialize(tweets)
#tweets = tweets
end
def each(&block) # Block into the proc
tweets.each(&block) # proc back into the block
end
end
I try to write DSL
class Warcraft
class << self
def config
unless #instance
yield(self)
end
#instance ||= self
end
attr_accessor :name, :battle_net
def game(&block)
#instance ||= Game.new(&block)
end
end
class Game
class << self
def new
unless #instance
yield
end
#instance ||= self
end
attr_accessor :side, :hero
def rune_appear_every(period)
#rune_appear_every = period
end
end
end
end
Warcraft.config do |war|
war.name = "Warcraft III"
war.battle_net = :iccup
war.game do |game|
game.side = :sentinels
game.hero = "Furion"
game.rune_appear_every 2.minutes
end
end
And i get such error:
dsl.rb:41:in `block (2 levels) in <main>': undefined method `side=' for nil:NilClass (NoMethodError)
The issue is here:
def new
unless #instance
yield
end
#instance ||= self
end
You're not passing in any argument when you yield, later on when you call:
war.game do |game|
The game variable is nil. So instead of just doing yield, do yield self.
I want to define a set of methods that can be added to a class (C in the example) using a Mixin. These methods can be defined by any class that inherits from another class (A in the example) and should be able to call methods in the receiver instance (C instance).
I have this snippet of code:
M = Module.new
class A
class << self
def init(method)
if block_given?
M.send(:define_method, method) do
instance_exec &Proc.new
end
else
block = self.method(method).to_proc
M.send(:define_method, method) do
yield block.call
end
end
end
end
end
class B < A
init(:foo) do
"foo+".concat(c_method)
end
def self.bar
"bar+".concat(c_method)
end
init(:bar)
end
C = Class.new do
def c_method
"c_method"
end
end
c = C.new
c.extend(M)
puts c.foo
puts c.bar
Adding methods using blocks works, but last line fails :(
foo+c_method
test.rb:28:in `bar': undefined local variable or method `c_method' for B:Class (NameError)
from test.rb:15:in `call'
from test.rb:15:in `block in init'
from test.rb:46:in `<main>'
What I'm doing wrong? Or this makes no sense?
Thanks
Juan
When you prepare instance_exec &Proc.new inside if statement, this statement is executed within instance of C class as context. You can verify this by adding puts self inside block for init(:foo).
On the other hand, when you call yield block.call you yield thread execution into context of B class object (not to instance of this class, of course :) ). This place of your code doesn't know anything about C::c_method and this is cause of error.
It seems that what I'm trying to do is to unbind the method :bar from B and bind to C, what it's not allowed. You can find more info in this great post
M = Module.new
class A
class << self
def init(method)
if block_given?
M.send(:define_method, method) do
instance_exec &Proc.new
end
else
block = self.method(method).unbind
M.send(:define_method, method) do
m = block.bind(self)
puts m
end
end
end
end
end
class B < A
init(:foo) do
"foo+".concat(c_method)
end
def self.bar
"bar+".concat(c_method)
end
init(:bar)
end
C = Class.new do
def c_method
"c_method"
end
end
c = C.new
c.extend(M)
puts c.foo
puts c.bar
foo+c_method
test.rb:16:in `bind': singleton method called for a different object (TypeError)
from test.rb:16:in `block in init'
from test.rb:48:in `<main>'
class Card
attr_accessor :number, :suit
def initialize(number, suit)
#number = number
#suit = suit
end
def to_s
"#{#number} of #{#suit}"
end
end
I'm assuming this creates a new array correct?
But why the use of the AT symbol? When should I use it and not use it?
#stack_of_cards = []
#stack << Card.new("A", "Spades")
puts #stack
# => BlackjackGame.rb:17: undefined method `<<' for nil:NilClass (NoMethodError)
Any ideas why this error is firing?
Exactly as it says in error: variable #stack is not defined (or nil).
Did you mean #stack_of_cards << .. instead?
If you had warnings on (ruby -W2 script_name.rb), you would have got a warning that #stack is not merely nil, but undefined. See How do I debug Ruby scripts? for more hints on how to debug.