Can I dynamically call a math operator in Ruby?

Question

Is there something like this in ruby?

send(+, 1, 2)

I want to make this piece of code seem less redundant

if op == \"+\"
           


        

Answer 1

As an other option, if your operator and operands happen to be in string format, say from a gets method, you can also use eval:

For example:

a = '1'; b = '2'; o = '+'

eval a+o+b

becomes

eval '1+2'

which returns 3

Answer 2

Yup, simply use send (or, better yet, public_send) like so:

arg1.public_send(op, arg2)

This works because most operators in Ruby (including +, -, *, /, and more) simply call methods. So 1 + 2 is the same as 1.+(2).

You may also want to whitelist op if it’s user input, e.g. %w[+ - * /].include?(op), as otherwise the user will be able to call arbitrary methods (which is a potential security vulnerability).