Ruby: Revise a rule related to optional arguments and keyword arguments

[nekketsuuu]

Rubocop 0.80.0 (released 2020-02-18) removed Style/BracesAroundHashParameters cop. rubocop/rubocop#7641 says the removal was because the curly braces may have the meaning since Ruby 2.7.

styleguide/.rubocop.yml

Lines 264 to 266 in 590bca6

	# [SHOULD] Omit `{ }` of a hash literal, when put on the end of an argument list.
	Style/BracesAroundHashParameters:
	EnforcedStyle: no_braces

I think it's a good time to reconsider the above rule.

My opinion is:

• Remove Style/BracesAroundHashParameters from .rubocop.yml.
• Rewrite the rule in English and Japanese to mention keyword arguments and hash. Ref: Revise "No Braces Options Hash" rule rubocop/ruby-style-guide#788

Any thoughts?

[nekketsuuu]

How about...

[SHOULD] Distinguish between using a hash and using keyword arguments in method calls.

def foo(a:, b:)
  p(a, b)
end

def bar(hash)
  p(hash)
end

# good
foo(a: 1, b: 2)
# good
bar({a: 1, b: 2})

# bad - foo expects keyword arguments, but it passes a hash
foo({a: 1, b: 2})
# bad - bar expects a hash, but it passes keyword arguments
bar(a: 1, b: 2)

The example above is a slightly modified version of rubocop/ruby-style-guide#788 (comment).

[mame]

Vote for the removal. The documents also looks great to me.