Index of an array containing an instance, from this instance

ruby-talk
1

Hi,

If I do this:

class Foo
end

my_array = []
my_array[8] = Foo.new

...From Foo instance, it is possible to get the array instance using
self, such with:

Class Foo
  def test
    puts "the array is: #{self}"
  end
end

my_array[8].test # => the array is: (something like fooooobaaaar)

...But is that possible to get its current indice (which is 8) where Foo
is stored? In other words, how can I get the current indice of the array
from Foo instance?

Thanks

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2

An object doesn't have any built-in notion of what other objects are referencing it. In your example the array would have a reference to the Foo instance but the Foo instance doesn't automatically have any reverse reference to the array. If you want/need that sort of thing you'll have to incorporate it into your implementation of Foo.

It is possible to search an array for a particular object and to return the index:

class Foo
end

my_array =
instance = Foo.new

my_array[8] = instance
puts "index: #{my_array.index(instance)}" # 8

Gary Wright

···

On Dec 30, 2009, at 5:13 PM, Paul A. wrote:

Hi,

If I do this:

class Foo
end

my_array =
my_array[8] = Foo.new

...From Foo instance, it is possible to get the array instance using
self, such with:

Class Foo
def test
   puts "the array is: #{self}"
end
end

my_array[8].test # => the array is: (something like fooooobaaaar)

...But is that possible to get its current indice (which is 8) where Foo
is stored? In other words, how can I get the current indice of the array
from Foo instance?

3

Thanks for this quick answer.

Happy end's year.

···

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