Optional argument/param in ruby

Question

I have method to which I want to pass an optional argument. By default I want to set that argument as nil. Here is the way I am doing it:

def my_function(arg1, arg2: nil)
  # Do something
end

I call the function as my_function(2, 5). I am getting an error which says: "wrong number of arguments (given 2, expected 1)"

Am I doing something wrong here? I wish to pass a value for arg2 during some calls and want it to be nil otherwise. So when I don't pass a value for arg2, my function call looks like my_function(2).

You can also use `my_function(2, arg2: 5)` – Sergio Tulentsev Aug 16 '16 at 14:45 — Sergio Tulentsev, Aug 16 '16 at 14:45

score 2 · Answer 1 · answered Aug 16 '16 at 14:43

2

Try out

def my_function(arg1, arg2 = nil)

answered Aug 16 '16 at 14:43

Ursus

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score 1 · Answer 2 · answered Aug 16 '16 at 14:47

You're defining a default keyword argument (vs a positional argument). You can call the function that you've defined with my_function(2) as well as my_function(2, arg2: 5). If you would like to use a positional argument you can define it as def my_function(arg1, arg2 = nil)

Here are some details on keyword arguments. https://robots.thoughtbot.com/ruby-2-keyword-arguments

Optional argument/param in ruby

2 Answers2