So I’ve learned Ruby and I am in love. And I just learned something that is going to make my life a whole lot easier and my scripts a lot less convoluted. Perhaps this was in one of the several books/tutorials I’ve read on the language, but I don’t remember it, or it was not presented in a way that seemed relevant to my applications.
My question was how do I get back to nameless, label-less objects based on their instance attributes? Here’s a silly example:
Here’s the definition of the Cat class:
attr_reader :name, :byear
def initialize(name, byear)
@name = name
@byear = byear
end #def initialize
end #class Cat
My initial array—I’ll call it catdata—looked like this:
[["Be", 1996], ["Cu", 1996], ["Hal", "unknown"], ["Felix", 1919]]
I created an array of Cat objects:
cats = 
catdata.each do |e|
newcat = Cat.new(e, e)
end #catdata.each do
Now cats is an array of mysterious objects:
[#<Cat:0x7ff6d324>, #<Cat:0x7ff6d34c>, ...etc]
My Problem: Variable names are not assigned to the Cat objects when they are created. How do I access those Cat objects using their instance attributes? For instance, if I want to pull out all the cats born in 1996, what do I do?
I’d come up with a very ugly workaround (don’t ask), but this is much, much cleaner and I believe it can easily be defined as a method for the Cat class. (And if there is an even better/more direct way to do this, please share!)
_1996cats = cats.find_all do |cat|
cat.instance_variable_get(:@byear) == 1996
The result is an array with two elements: the objects for Be and Cu. Hooray!