Are there more elegant ways to prevent negative numbers in Ruby? -

given i'd following calculation:

total = subtotal - discount 

because discount might greater subtotal, there code following:

class calculator   def initialize(subtotal: subtotal, discount: discount)     @subtotal = subtotal     @discount = discount   end    def total     [subtotal - discount, 0].max   end    private    def subtotal     @subtotal   end    def discount     @discount   end end 

when seeing [subtotal - discount, 0].max part or similar code, have pause , think.

are there more elegant ways handle kind of calculation?

thinking can extend numeric class?

class numeric                                                                     def non_negative                                                                  self > 0 ? self : 0                                                                         end                                                                           end                                                                              class calculator   def initialize(subtotal: subtotal, discount: discount)     @subtotal = subtotal     @discount = discount   end    def total     (@subtotal - @discount).non_negative   end end