Undefined method `-' for nil

ruby-talk
1

Hi guys.

So I've hit a brick wall with a simple piece of code and hope someone
here can shed some light on what's going wrong ...

···

***************************************************
developer_object_array.each do |dev|
    if dev.is_solvent? == false
      then puts("#{dev.name} is bankrupt.")
        dev.bankrupt = true
        bank_object_array.each do |bank|
          bank.moves_loans(amount)
    else puts("#{dev.name} is not bankrupt.")
    end
  end
*********************************************************

I have the above piece of code in a class. Inside this class I create
and array of Bank and Developer objects. When the code gets to
bank.move_loans
I get an "undefined method `-' for nil:NilClass (NoMethodError" error.

The move_loans method is defined in the Bank class just does some basic
subtraction on the value passed to it.

I've no idea what the error is, as I've torn through every piece of code
in the classes and can't see anything wrong.

Any ideas would be great!! Thanks!

--
Posted via http://www.ruby-forum.com/.

2

Really need to see what the developer objects and bank objects look like, and how/ where the bank_object_array gets populated.

Sam

···

On 10/09/2012 09:13 AM, Joz Private wrote:

Hi guys.

So I've hit a brick wall with a simple piece of code and hope someone
here can shed some light on what's going wrong ...

***************************************************
developer_object_array.each do |dev|
     if dev.is_solvent? == false
       then puts("#{dev.name} is bankrupt.")
         dev.bankrupt = true
         bank_object_array.each do |bank|
           bank.moves_loans(amount)
     else puts("#{dev.name} is not bankrupt.")
     end
   end
*********************************************************

I have the above piece of code in a class. Inside this class I create
and array of Bank and Developer objects. When the code gets to
bank.move_loans
I get an "undefined method `-' for nil:NilClass (NoMethodError" error.

The move_loans method is defined in the Bank class just does some basic
subtraction on the value passed to it.

I've no idea what the error is, as I've torn through every piece of code
in the classes and can't see anything wrong.

Any ideas would be great!! Thanks!

3

Go into the function: bank.moves_loans
and for each '-' operation check operand, I am 100 % sure that one of
the operand becomes NIL at some point.

Looking at your question, I would like to give an explicit answer, which
is not expected here:

for each statement involving '-' viz:
a=b-c
replace it by:
if b==nil or c==nil
  puts "My 100% is proved, here is the error"
else
  a=b-c
end

···

--
Posted via http://www.ruby-forum.com/.

4

Don't mind the extra fields in the Bank object creation, they're not
supposed to be there

···

--
Posted via http://www.ruby-forum.com/.

5

class Developer
  attr_accessor :name, :networth, :loans, :banks_loaned_from, :bankrupt

  def initialize(name, networth, loans, banks_loaned_from, bankrupt)
  @name, @networth, @loans, @banks_loaned_from, @bankrupt = name,
networth, loans, banks_loaned_from, bankrupt
  end

  def is_solvent?
    if networth >= owes_amount
      then true
    else false
    end
  end

        def owes_amount
    total_loans = 0
    loans_array = loans.split(',')
    loans_array.each { |item| total_loans += item.to_f }
    total_loans
  end

  def owes_bank(bank)
    loans_array = loans.split(',')
    banks_array = banks_loaned_from.split(',')
    banks_array.each do |item|
      if bank == item
        then i = banks_array.index(item)
        loans_array[i].to_f
      else
        puts("No such bank - check name.")
      end
    end
  end

end

···

**************************************************************************
**************************************************************************
class Bank
  attr_accessor :name, :amount_of_deposits, :amount_of_loans

  def initialize(name, amount_of_deposits, amount_of_loans)
    @name, @amount_of_deposits, @amount_of_loans, = name,
amount_of_deposits, amount_of_loans
  end

  def moves_loans(amount)
    amount_of_loans -= amount
    amount_of_deposits += (amount*0.5)
  end

  def bank_is_solvent?
    if amount_of_deposits >= amount_of_loans
      true
    else
      false
    end
  end

end
**************************************************************************
**************************************************************************
require_relative '.\Bank.rb'
require_relative '.\Developers.rb'

class Bankrupter

  # creating the developers
  L = Developer.new("L", 650000, "1500000, 500000, 1000000, 300000",
"AIB,BOI,Ulster,Anglo", false)
  M = Developer.new("M", 2100000, "1400000, 2000000", "AIB,Anglo",
false)
  R = Developer.new("R", 900000, "500000, 700000, 1000000, 1200000",
"AIB,BOI,RSB,Anglo", false)
  MF = Developer.new("MF", 1200000, "400000, 2000000, 8000000",
"AIB,Ulster,Anglo", false)
  MN = Developer.new("MN", 3000000, "100000, 300000", "BOI,RSB", false)

  # creating the banks
  AIB = Bank.new("AIB", 450, 3000000, 500000, false)
  Anglo = Bank.new("Anglo", 520, 5000000, 12000000, false)
  BOI = Bank.new("BOI", 600, 2500000, 2500000, false)
  RBS = Bank.new("RBS", 530, 2800000, 1700000, false)
  Ulster = Bank.new("Ulster", 580, 2000000, 1500000, false)

  developer_object_array = [ L, M, R, MF, MN]
  bank_object_array = [ AIB, Anglo, BOI, RBS, Ulster ]

  #Now, test if they are solvent or bankrupt, and then the knock-on
effects for the banks ...

  developer_object_array.each do |dev|
    if dev.is_solvent? == false
      then puts("#{dev.name} is bankrupt.")
        dev.bankrupt = true
        bank_object_array.each do |bank|
          bank.moves_loans
        end
    else puts("#{dev.name} is not bankrupt.")
    end
  end

end

--
Posted via http://www.ruby-forum.com/.

6

Well for a start, Bank#moves_loans method takes an 'amount' argument which you don't appear to be passing. I wouldn't be assigning your bank and developer instances to constants either (variable names starting with upper case letters are implicitly constants in Ruby). Also, the constructor for the Bank object takes 3 values, however you are passing them 5?

Sam

···

On 10/09/2012 09:35 AM, Joz Private wrote:

class Developer
   attr_accessor :name, :networth, :loans, :banks_loaned_from, :bankrupt

   def initialize(name, networth, loans, banks_loaned_from, bankrupt)
   @name, @networth, @loans, @banks_loaned_from, @bankrupt = name,
networth, loans, banks_loaned_from, bankrupt
   end

   def is_solvent?
     if networth >= owes_amount
       then true
     else false
     end
   end

         def owes_amount
     total_loans = 0
     loans_array = loans.split(',')
     loans_array.each { |item| total_loans += item.to_f }
     total_loans
   end

   def owes_bank(bank)
     loans_array = loans.split(',')
     banks_array = banks_loaned_from.split(',')
     banks_array.each do |item|
       if bank == item
         then i = banks_array.index(item)
         loans_array[i].to_f
       else
         puts("No such bank - check name.")
       end
     end
   end

end
**************************************************************************
class Bank
   attr_accessor :name, :amount_of_deposits, :amount_of_loans

   def initialize(name, amount_of_deposits, amount_of_loans)
     @name, @amount_of_deposits, @amount_of_loans, = name,
amount_of_deposits, amount_of_loans
   end

   def moves_loans(amount)
     amount_of_loans -= amount
     amount_of_deposits += (amount*0.5)
   end

   def bank_is_solvent?
     if amount_of_deposits >= amount_of_loans
       true
     else
       false
     end
   end

end
**************************************************************************
require_relative '.\Bank.rb'
require_relative '.\Developers.rb'

class Bankrupter

   # creating the developers
   L = Developer.new("L", 650000, "1500000, 500000, 1000000, 300000",
"AIB,BOI,Ulster,Anglo", false)
   M = Developer.new("M", 2100000, "1400000, 2000000", "AIB,Anglo",
false)
   R = Developer.new("R", 900000, "500000, 700000, 1000000, 1200000",
"AIB,BOI,RSB,Anglo", false)
   MF = Developer.new("MF", 1200000, "400000, 2000000, 8000000",
"AIB,Ulster,Anglo", false)
   MN = Developer.new("MN", 3000000, "100000, 300000", "BOI,RSB", false)

   # creating the banks
   AIB = Bank.new("AIB", 450, 3000000, 500000, false)
   Anglo = Bank.new("Anglo", 520, 5000000, 12000000, false)
   BOI = Bank.new("BOI", 600, 2500000, 2500000, false)
   RBS = Bank.new("RBS", 530, 2800000, 1700000, false)
   Ulster = Bank.new("Ulster", 580, 2000000, 1500000, false)

   developer_object_array = [ L, M, R, MF, MN]
   bank_object_array = [ AIB, Anglo, BOI, RBS, Ulster ]

   #Now, test if they are solvent or bankrupt, and then the knock-on
effects for the banks ...

   developer_object_array.each do |dev|
     if dev.is_solvent? == false
       then puts("#{dev.name} is bankrupt.")
         dev.bankrupt = true
         bank_object_array.each do |bank|
           bank.moves_loans
         end
     else puts("#{dev.name} is not bankrupt.")
     end
   end

end

7

Sam Duncan wrote in post #1079016:

       then true

     end
amount_of_deposits, amount_of_loans
     else
class Bankrupter
   MN = Developer.new("MN", 3000000, "100000, 300000", "BOI,RSB", false)
   bank_object_array = [ AIB, Anglo, BOI, RBS, Ulster ]
         end
     else puts("#{dev.name} is not bankrupt.")
     end
   end

end

Well for a start, Bank#moves_loans method takes an 'amount' argument
which you don't appear to be passing. I wouldn't be assigning your bank
and developer instances to constants either (variable names starting
with upper case letters are implicitly constants in Ruby). Also, the
constructor for the Bank object takes 3 values, however you are passing
them 5?

My bad, I just copied the code wrong .... assuming I have all that fixed
...

I've stumbled on this:

The move_loans method works if I use this code below as I get the
output:

def move_loans
     puts(amount_of_loans - amount)
end

But if I replace the body with what I really want, it throws the error:

def moves_loans
     amount_of_loans = amount_of_loans - amount
end

It seems to be THAT body right there that's throwing the error...what's
going on??!!

···

On 10/09/2012 09:35 AM, Joz Private wrote:

Sam

--
Posted via http://www.ruby-forum.com/\.

8

It is very confusing what the code actually looks like. Do you think you could put the whole lot up as a gist on github or some other pastebin type bizzo? It is not clear where the 'amount' value comes from in that method now for a start =]

Sam

···

On 10/09/2012 10:22 AM, Joz Private wrote:

Sam Duncan wrote in post #1079016:

On 10/09/2012 09:35 AM, Joz Private wrote:

        then true

      end
amount_of_deposits, amount_of_loans
      else
class Bankrupter
    MN = Developer.new("MN", 3000000, "100000, 300000", "BOI,RSB", false)
    bank_object_array = [ AIB, Anglo, BOI, RBS, Ulster ]
          end
      else puts("#{dev.name} is not bankrupt.")
      end
    end

end

Well for a start, Bank#moves_loans method takes an 'amount' argument
which you don't appear to be passing. I wouldn't be assigning your bank
and developer instances to constants either (variable names starting
with upper case letters are implicitly constants in Ruby). Also, the
constructor for the Bank object takes 3 values, however you are passing
them 5?

My bad, I just copied the code wrong .... assuming I have all that fixed
...

I've stumbled on this:

The move_loans method works if I use this code below as I get the
output:

def move_loans
      puts(amount_of_loans - amount)
end

But if I replace the body with what I really want, it throws the error:

def moves_loans
      amount_of_loans = amount_of_loans - amount
end

It seems to be THAT body right there that's throwing the error...what's
going on??!!

Sam

9

Here amount_of_loans is understoos as a local variable, since you have
an assigment, so the amount_of_loans at the right hand side gets
evaluated to nil. I guess you want the instance variable, so:

def moves_loans
  @amount_of_loans = @amount_of_loans - amount
end

or

def moves_loans
  @amount_of_loans -= amount
end

Jesus.

···

On Mon, Oct 8, 2012 at 11:22 PM, Joz Private <lists@ruby-forum.com> wrote:

def moves_loans
     amount_of_loans = amount_of_loans - amount
end

10

Sam Duncan wrote in post #1079021:

···

On 10/09/2012 10:22 AM, Joz Private wrote:

          end

constructor for the Bank object takes 3 values, however you are passing

def move_loans
going on??!!

Sam

It is very confusing what the code actually looks like. Do you think you
could put the whole lot up as a gist on github or some other pastebin
type bizzo? It is not clear where the 'amount' value comes from in that
method now for a start =]

Sam

Sorry, I really messed up copying the code :stuck_out_tongue:

The amount gets passed as in:

bank.moves_loans(dev.owes_bank(bank.name))

^^^That's what should be in Bankrupter class above!

--
Posted via http://www.ruby-forum.com/\.