Accessing instance variables in Ruby OOP

Question

I am learning Ruby OOP and have been faced with the following question.

What could we add to the class below to access the instance variable @volume?

class Cube
  def initialize(volume)
    @volume = volume
  end
end

My initial thought was to add attr_reader :volume to access the instance variable.

Instead the model answer suggests adding a new method as below.

def get_volume
  @volume
end

Why is this the preferred method? Both methods would output 100 if cube.volume or cube.get_volume were called.

The resource you're learning this from is crap.

doesterr
– doesterr

2015-09-05 10:37:52 +00:00
Commented Sep 5, 2015 at 10:37 — doesterr
– doesterr, Commented Sep 5, 2015 at 10:37

djaszczurowski · Accepted Answer · 2015-09-05 10:25:18Z

5

attr_reader. In general methods with get_ prefix are rather avoided in Ruby community (in opposite to commonly seen in Java/C# code)

answered Sep 5, 2015 at 10:25

djaszczurowski

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1 Comment

djaszczurowski Over a year ago

Yes, exactly as you thought.

Vishnu Atrai · Accepted Answer · 2015-09-05 13:16:40Z

0

If it is a dynamically created variable, then you can use instance_vairable_get, like below -

instance_variable_get("@volume")

answered Sep 5, 2015 at 13:16

Vishnu Atrai

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Comments

Olalekan Sogunle · Accepted Answer · 2019-02-12 16:21:03Z

0

Since it is desired to get the variable volume ,I will suggest the use of attr_reader :volume. This creates a proxy method volume so no need to add( and later have to maintain) an extra method get_volume for this sole purpose.

https://ruby-doc.org/core-2.1.1/Module.html#method-i-attr_reader

answered Feb 12, 2019 at 16:21

Olalekan Sogunle

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Rushikesh k · Accepted Answer · 2021-05-04 10:35:09Z

0

You should use attr_reader :volume instead of using get_volume method. Stil attr_reader and your method get_volume both are functioning same. Generally get_ methods should be avoided in ruby.

answered May 4, 2021 at 10:35

Rushikesh k

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