Question

I have a method in which i want to pass in dynamic params. The method is called in a loop and sometimes value2 is available and sometimes not.

What is the common way to handle optional method params?

my_method(:value1 => 1,
          :value2 => 2 if foo,  # this is not working
          :value3 => 3)

Answer 1

I usually create a hash like this:

opts = {:value1 => 1, 
        :value3 => 3}
opts[:value2] = 2 if foo
my_method(opts)

The benefit of this approach is that everyone catches the if foo as it is a special case. Otherwise many programmers, like myself, will miss this at first glance and get confused why :value2 is not set.

Sometimes you have default settings, then you can use this approach:

default = {:value1 => 0,
           :value2 => 0,
           :value3 => 0}
opts = {:value1 => 1, 
        :value3 => 3}
my_method(default.merge(opts))

Or even better:

DEFAULT_OPTS = {:value1 => 0,
                :value2 => 0,
                :value3 => 0}

def my_method(opts)
  opts = DEFAULT_OPTS.merge(opts)
  # ...
end

my_method(...)