Project

General

Profile

Actions

Feature #18402

open

Argument Labels

Added by Lomig (Lomig Enfroy) over 2 years ago. Updated about 2 years ago.

Status:
Open
Assignee:
-
Target version:
-
[ruby-core:106614]

Description

As a developer, I mainly program in two languages: Swift and Ruby.

I love Ruby with all my heart, but I came to like a particular feature of Swift: Argument labels ; I would love to see them appear in Ruby.
Matz on Twitter suggested I post a feature request, so here we are!

Context

Naming is hard.
Keyword arguments helps defining methods that are readable and allow for flexibility ordering arguments, but the result may be a little too verbose as I use to create methods like:

def change_color_for_user_until_date(new_color:, user:, end_date:)
  do_something_with(new_color)
  do_something_else_with(user, end_date)
end

change_color_for_user_until_date(new_color: :blue, user: user, end_date: DateTime.tomorrow)

Also, that's not as readable in a "natural way" as plenty of code we can produce with Ruby.

Copying Swift, I would love to have argument labels, aka the option to define a different name for the argument and its related parameter.

Right now

This code is a no-go, as it would be a nightmare to maintain:
(the code below is using reserved keywords so would not work in reality, but it's for the sake of clarity and the sake of the example)

def change_color(to:, for:, until:)
  new_color, user, end_date = to, for, until

  do_something_with(to)
  do_something_else_with(for, until)  # What does this do with which data again?
end

change_color(to: :blue, for: user, until: DateTime.tomorrow)

This being said, I can simulate such a behaviour this way:
(the code below is using reserved keywords so would not work in reality, but it's for the sake of clarity and the sake of the example)

def change_color(to:, for:, until:)
  new_color, user, end_date = to, for, until # well, those are reserved keywords, I would never be able to use them like that

  do_something_with(new_color)
  do_something_else_with(user, end_date)
end

change_color(to: :blue, for: user, until: DateTime.tomorrow)

That's not perfect though:

  • Not standardized enough
  • Conflict with reserved keywords (in reality, I would try to find synonyms? change_color(with: :blue, regarding: user, up_until: DateTime.tomorrow) ?)
  • An extra line, and not so elegant

The feature request mirroring Swift

It does not have to be implemented exactly this way, of course!

def change_color(to new_color:, for user:, until end_date:)

  do_something_with(new_color)
  do_something_else_with(user, end_date) # No use of reserved keywords anymore, and readable variable name!
end

change_color(to: :blue, for: user, until: DateTime.tomorrow)

Thanks in advance for your insight on this matter,
Cheers!


Related issues 1 (1 open0 closed)

Related to Ruby master - Feature #17785: Allow named parameters to be keywordsOpenmatz (Yukihiro Matsumoto)Actions
Actions

Also available in: Atom PDF

Like0
Like0Like0Like0Like0Like0Like0Like0Like1