Using index value in method - ruby-on-rails

Question

In my Rails application, in a model, I am trying to use the loop index x in the following method, and I can't figure out how to get the value:
def set_winners ## loops over 4 quarters
1.upto(4) do |x|
qtr_[x]_winner.winner = 1
qtr_[x]_winner.save
end
end
I'm going to keep searching but any help would be greatly appreciated!
edit: So I guess I can't do that! Here is the original method I was trying to refactor in full by looping four times:
def set_winners
## set all 4 quarter's winning squares
home_qtr_1 = game.home_q1_score.to_s.split('').last.to_i
away_qtr_1 = game.away_q1_score.to_s.split('').last.to_i
qtr_1_winner = squares.where(xvalue:home_qtr_1, yvalue:away_qtr_1).first
qtr_1_winner.winner = 1
qtr_1_winner.save
home_qtr_2 = game.home_q2_score.to_s.split('').last.to_i
away_qtr_2 = game.away_q2_score.to_s.split('').last.to_i
qtr_2_winner = squares.where(xvalue:home_qtr_2, yvalue:away_qtr_2).first
qtr_2_winner.winner = 1
qtr_2_winner.save
home_qtr_3 = game.home_q3_score.to_s.split('').last.to_i
away_qtr_3 = game.away_q3_score.to_s.split('').last.to_i
qtr_3_winner = squares.where(xvalue:home_qtr_3, yvalue:away_qtr_3).first
qtr_3_winner.winner = 1
qtr_3_winner.save
home_qtr_4 = game.home_q4_score.to_s.split('').last.to_i
away_qtr_4 = game.away_q4_score.to_s.split('').last.to_i
qtr_4_winner = squares.where(xvalue:home_qtr_4, yvalue:away_qtr_4).first
qtr_4_winner.winner = 1
qtr_4_winner.save
end
Is there a better way to do this if it's bad practice to dynamically change attribute names?

Answer 1

It looks like you are trying to do a PHP-like trick in a language that doesn't support it, and where we recommend NOT doing it because it results in code that is very difficult to debug due to the dynamically named variables.
It looks like you want to generate a variable name using:
qtr_[x]_winner
to create something like:
qtr_1_winner
Instead, consider creating an array named qtr_winner containing your objects and access the elements like:
qtr_winner[1]
or
qtr_winner[2]
etc.
You could create a hash to do a similar thing:
qtr_winner = {}
qtr_winner[1] = 5
then later access it using qtr_winner[1] and get 5 back or
qtr_winner[1].winner = 1
The determination of whether to use a hash or an array is whether you need to walk the container, or need random access. If you are always indexing into it using a value, then it's probably a wash about which is faster.

Answer 2

Based on your edit, you don't need dynamic variables. The only thing that changes in your loop is game.home_qN_score, so that's what the focus of your refactoring should be. Given that, here's a viable solution:
1.upto(4) do |i|
home_qtr = game.send("home_q#{i}_score)".to_s.split('').last.to_i
away_qtr = game.send("away_q#{i}_score)".to_s.split('').last.to_i
winner = squares.where(xvalue:home_qtr, yvalue:away_qtr).first
winner.winner = 1
winner.save
end
Original answer:
If qtr_1_winner, etc. are instance methods, you can use Object#send to achieve what you want:
def set_winners ## loops over 4 quarters
1.upto(4) do |x|
send("qtr_#{x}_winner").winner = 1
send("qtr_#{x}_winner").save
end
end