How do I give a instance variable a default value

Ruby
#1 
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Hello,

I have this :

class Account
  attr_reader :name
  attr_reader :balance
 
  def initialize (name, balance)
      @name = name
      @balance = balance
      balance = 100
  end

end

But when I run it I see this error message : Oops, try again. Did you give your initialize method's balance parameter a default value?

Can anyone explain to me what I did wrong ?

Roelof

#2

On Mon, May 26, 2014 at 5:46 PM, Roelof W. [email protected] wrote:

  @balance = balance
  balance = 100

end

end

But when I run it I see this error message : Oops, try again. Did you give
your initialize method’s balance parameter a default value?

Can anyone explain to me what I did wrong ?

I cannot reproduce:

2.0.0p195 :001 > class Account
2.0.0p195 :002?> attr_reader :name
2.0.0p195 :003?> attr_reader :balance
2.0.0p195 :004?>
2.0.0p195 :005 > def initialize (name, balance)
2.0.0p195 :006?> @name = name
2.0.0p195 :007?> @balance = balance
2.0.0p195 :008?> balance = 100
2.0.0p195 :009?> end
2.0.0p195 :010?>
2.0.0p195 :011 > end

2.0.0p195 :013 > Account.new “test”, 150
=> #<Account:0x000000013e8ab8 @name=“test”, @balance=150>
2.0.0p195 :014 > Account.new(“test”, 150).balance
=> 150

In what kind of environment are you testing this? The “Ooops, try
again” message seems very weird to me…

Jesus.

#3

@Jesus it seems to me he is using an online tutorial/trainer that
prompts
for a certain change and responds based on user action

@Roelof take a look at
http://en.wikibooks.org/wiki/Ruby_Programming/Syntax/Method_Calls#Default_Values

On Mon, May 26, 2014 at 11:58 AM, Jesús Gabriel y Galán <

#4

I have never seen the “Oops” message either. Maybe this what you are
looking for:

def initialize (name, balance=100)

On Mon, May 26, 2014 at 11:58 AM, Jesús Gabriel y Galán <

#5
Thanks , too clarify. Im using CodeAcademy to learn Ruby.

Another problem.

You can do this

x = y ? puts x : puts y

but what if you want to do multple things like this

x = y ? x -= 1; puts x : y-= 1 ; puts y

I see then a error message that the ; is found where a : is expected
folding it into {} also do not seem to do the trick.

Roelof



Marian Mosley schreef op 26-5-2014 18:05:
I have never seen the "Oops" message either.?? Maybe this what you are looking for:

def initialize (name, balance=100)


On Mon, May 26, 2014 at 11:58 AM, Jes??s Gabriel y Gal??n <[email protected]> wrote:
On Mon, May 26, 2014 at 5:46 PM, Roelof Wobben <[email protected]> wrote:
> Hello,
>
> I have this :
>
> class Account
> ?? attr_reader :name
> ?? attr_reader :balance
>
> ?? def initialize (name, balance)
> ?? ?? ?? @name = name
> ?? ?? ?? @balance = balance
> ?? ?? ?? balance = 100
> ?? end
>
> end
>
> But when I run it I see this error message : Oops, try again. Did you give
> your initialize method's balance parameter a default value?
>
> Can anyone explain to me what I did wrong ?

I cannot reproduce:

2.0.0p195 :001 > class Account
2.0.0p195 :002?> ?? ?? attr_reader :name
2.0.0p195 :003?> ?? ?? attr_reader :balance
2.0.0p195 :004?>
2.0.0p195 :005 > ?? ?? ?? def initialize (name, balance)
2.0.0p195 :006?> ?? ?? ?? ?? ?? @name = name
2.0.0p195 :007?> ?? ?? ?? ?? ?? @balance = balance
2.0.0p195 :008?> ?? ?? ?? ?? ?? balance = 100
2.0.0p195 :009?> ?? ?? ?? end
2.0.0p195 :010?>
2.0.0p195 :011 > ?? ?? end

2.0.0p195 :013 > Account.new "test", 150
??=> #<Account:0x000000013e8ab8 @name="test", @balance=150>
2.0.0p195 :014 > Account.new("test", 150).balance
??=> 150


In what kind of environment are you testing this? The "Ooops, try
again" message seems very weird to me...

Jesus.


#6

On Mon, May 26, 2014 at 7:15 PM, Roelof W. [email protected] wrote:

x = y ? x -= 1; puts x : y-= 1 ; puts y

I see then a error message that the ; is found where a : is expected
folding it into {} also do not seem to do the trick.

You need to use parenthesis:

x == y ? (x -= 1; puts x) : (y-= 1 ; puts y)

By the way, I think you are missing one equals sign in the condition,
otherwise it’s an assignment, so it will be true unless y is nil.

Jesus.

#7

You are setting value of balance attribute (instead of instance
variable)
to 100, but it’s never used, so you can delete that line.

To make an attribute optional and give it a default value, you must
provide
that value in method definition:

def initialize(name, balance=100)
…
…

I hope this helps :slight_smile: