CODEWITHSUNDEEP
ruby
Strictly No Lollygagging
Strictly No Lollygagging

Reputation: 301

Dynamically creating objects in Ruby

I have a class whose initialize method defines a few instance variables and does some calculations. I need to create about 60 objects of that class. Each object has an ID number at the end. E.g.:

object1 = Dynamic.new(x, y)
object2 = Dynamic.new(x, y)
object3 = Dynamic.new(x, y)
...

I could just define them all by hand, but that would be quite inefficient. Is there any way to dynamically create each object?

Upvotes: 3

Views: 2594

Answers (3)

TheLuigi
TheLuigi

Reputation: 46

You can always make a loop and push all the objects into an array. An array position might also be needed for knowing which object is each. This isn't quite what you wanted (atleast I don't think so), but it should suffice.

class Dynamic
@@instances_of_class = 0
  def initialize(x,y)
  #...
  @array_position = @@instances_of_class
  @@instances_of_class += 1
  end
end

ary = []
50.times do 
ary << Dynamic.new(x,y)
end

Edit: This solution, as said in the comments, can cause bugs if you change the array, so here's an alternate solution.

require 'File.rb'
i = 1
varFile = File.open("File.rb","a+")
50.times do
varFile.puts "variable#{i} = Object.new"
i += 1
end

Inside of File.rb will be 50 uniquely named variables that you can use.

Upvotes: 3

Ramfjord
Ramfjord

Reputation: 939

I would be curious to know why you need this. It's an unusual requirement, and often that means that you can avoid the problem instead of solving it. I think TheLuigi's solution would work, but if you use a class variable then these Id's will be shared across multiple classes. You can instead use an instance variable, with something like the following:

class A
  def self.next_id
    @id ||= 0 ; @id += 1
  end

  def initialize
    @id = A.next_id
  end
end

A.new
# => #<A:0x007fd6d414c640 @id=1>
A.new
# => #<A:0x007fd6d41454a8 @id=2>

Upvotes: 1

sawa
sawa

Reputation: 168101

If you just want sixty objects accessible from a variable, you should have them in an array referred to by a single variable.

objects = Array.new(60){Dynamic.new(x, y)}

Your object1, object2, ... will correspond to objects[0], objects[1], ... respectively.

Upvotes: -1

Related Questions