Pattern matching support for arguments

[rgarner]

Implement Rake::TaskArguments#deconstruct_keys. This means in an idiomatic ruby 3.x rake task we can use rightward assignment to say:

task :get, %i[tenant id] do |_t, args|
  args => {tenant:, id:}
  ...
end

... and omit the .to_h from args, raising NoMatchingPatternError if either of the two params is absent from the task args.

[nevans]

#deconstruct_keys should handle keys == nil, or **rest will be broken.

# normal behavior:
{a: 1, b: 2, c: 3} => {a:, **rest}
a     # => 1
rest  # => {b: 2, c: 3}

# without handling `keys == nil`
class Example
   def initialize(hash) = @hash = hash
   def deconstruct_keys(keys) = @hash.slice(*keys)
end

Example.new({a: 1, b: 2, c: 3}) => {a:, **rest}
# !=> #<Example:0x00007479b6b781b8 @hash={a: 1, b: 2, c: 3}>: key not found: :a (NoMatchingPatternKeyError)

(My apologies for not creating a PR... I can do that later today.)

[nevans]

This should handle the nil case, too:

Suggested change

	def deconstruct_keys(keys)
	@hash.slice(*keys)
	end
	def deconstruct_keys(keys)
	keys ? @hash.slice(*keys) : @hash.dup
	end

[Yltrik]

?

[nevans]

This should check the nil case, too:

Suggested change

	assert_equal ta.deconstruct_keys([:a, :b]), { a: 1, b: 2 }
	assert_equal ta.deconstruct_keys(nil), { a: 1, b: 2, c: 3 }
	assert_equal ta.deconstruct_keys([:a, :b]), { a: 1, b: 2 }

[nevans]

Okay, I did create a small PR to handle the nil case: #635.

Thanks for this PR, @rgarner! I'm a big fan of adding #deconstruct and/or #deconstruct_keys everywhere they make sense. 🙂

[rgarner]

Great shout @nevans, thanks for spotting. I rarely use the **rest case and was unaware of the nil semantics but will take this lesson with me!