Passing hashes instead of method parameters [closed]

I see that in Ruby (and dynamically typed languages, in general) a very common practice is to pass a hash, instead of declaring concrete method parameters. For example, instead of declaring a method with parameters and calling it like this:

def my_method(width, height, show_border)
my_method(400, 50, false)

you can do it this way:

def my_method(options)
my_method({"width" => 400, "height" => 50, "show_border" => false})

I'd like to know your opinion about it. Is it a good or a bad practice, should we do it or not? In what situation using this practice is valid, and it what situation can it be dangerous?

Solution 1:

Ruby has implicit hash parameters, so you could also write

def my_method(options = {}) 

my_method(:width => 400, :height => 50, :show_border => false)

and with Ruby 1.9 and new hash syntax it can be

my_method( width: 400, height: 50, show_border: false )

When a function takes more than 3-4 parameters, it's much easier to see which is what, without counting the respective positions.

Solution 2:

Both approaches have their own advantages and disadvantages, when you use an options hash replacing standard arguments you lose clarity in the code defining the method but gain clarity whenever you use the method because of the pseudo-named paramaters created by using an options hash.

My general rule is if you either have a lot of arguments for a method (more than 3 or 4) or lots of optional arguments then use an options hash otherwise use standard arguments. However when using an options hash it is important to always include a comment with the method definition describing the possible arguments.