CODEWITHSUNDEEP
ruby
Ahmad Al-kheat
Ahmad Al-kheat

Reputation: 1795

Ruby map method with instance_variables

Say I have a class SomeClass with instance variables a and b.

def SomeClass
  def initialize a, b
    @a = a
    @b = b
  end
end

When I type into pry the following lines

someclass = SomeClass.new "one", "two"
someclass.instance_variables

As expected it prints an array with symbols 

[:@a, :@b]

now, when I use 

a.instance_variables.map do |var|
  puts var
end

I expect it to print

:@a
:@b

but what I am getting is 

@a
@b

Can someone please explain this behaviour ?

Upvotes: 0

Views: 214

Answers (2)

Lakshmi
Lakshmi

Reputation: 361

If you just want to print the symbols as
:@a
:@b
use 'p var', as p calls inspect on its argument unlike puts which calls to_s

Upvotes: 2

Aleksei Matiushkin
Aleksei Matiushkin

Reputation: 121000

puts transparently calls to_s on arguments. Symbol#to_s returns symbol’s name (strings w/out preceding colon.) On the other hand, Array#to_s calls inspect on nested elements, that’s why you see colons while putting array’s instance.

Look:

▶ :a.to_s
#=> "a"
▶ [:a,:b,:c].to_s
#=> "[:a, :b, :c]"

This is exactly what you yield calling puts.

Upvotes: 2

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