The Book of Ruby

Potential Side Effects of Reliance on Argument Values

For a simple (but, in real-world programming, potentially serious) example of how relying on the modified values of arguments rather than on explicit return values can introduce undesirable dependencies on implementation details, see side_effects.rb. Here is a method called stringProcess that takes two string arguments, messes about with them, and returns the results:

side_effects.rb

def stringProcess( aStr, anotherStr )
    aStr.capitalize!
    anotherStr.reverse!.capitalize!
    aStr = aStr +  " " + anotherStr.reverse!
    return aStr
end

Let’s assume the object of the exercise is to take two lowercase strings and return a single string that combines these two strings, separated by a space and with the first ...