PatternMatchable

call method with pattern match.

Installation

Add this line to your application's Gemfile:

gem 'pattern_matchable'

And then execute:

$ bundle install

Or install it yourself as:

$ gem install pattern_matchable

Usage

require "pattern_matchable"

using PatternMatchable Array

case [1, 2, 3]
in first:, last:
  pp "OK : #{first}, #{last}"
  # => "OK : 1, 3"
end

1. using PatternMatchable {class names}

Use Refinements to add {class names}#deconstruct_keys.

require "pattern_matchable"

# define Array#deconstruct_keys
using PatternMatchable Array

[1, 2, 3, 4, 5] => { first:, last: }
p first  # => 1
p last   # => 5

"Homu" in { downcase:, upcase: }
# => false

2. using PatternMatchable

Use Refinements to add Object#deconstruct_keys.

require "pattern_matchable"

# defined Object#deconstruct_keys
using PatternMatchable

case [1, 2, 3, 4, 5]
in { first:, last: }
end
p first  # => 1
p last   # => 5

case "Homu"
in { downcase:, upcase: }
end
p downcase   # => "homu"
p upcase     # => "HOMU"

3. include PatternMatchable

include and add #deconstruct_keys to any class / module.

require "pattern_matchable"

# mixin PatternMatchable to Array
# defined Array#deconstruct_keys
class Array
  include PatternMatchable
end

# OK: assigned `first` `last` variables
case [1, 2, 3, 4, 5]
in { first:, last: }
end
p first  # => 1
p last   # => 5

# error: NoMatchingPatternError
case "Homu"
in { downcase:, upcase: }
end

4. using PatternMatchable.refining klass

Add #deconstruct_keys to any class / module using Refinements.

require "pattern_matchable"

# define Array#deconstruct_keys
using PatternMatchable.refining Array

[1, 2, 3, 4, 5] => { first:, last: }
p first  # => 1
p last   # => 5

# error: NoMatchingPatternError
case "Homu"
in { downcase:, upcase: }
end

5. using PatternMatchable::#{class name}

Use Refinements using const_missing.

require "pattern_matchable"

# define Array#deconstruct_keys
using PatternMatchable::Array

case [1, 2, 3, 4, 5]
in { first:, last: }
end
p first  # => 1
p last   # => 5

# nested class name
# defined Enumerator::Lazy
using PatternMatchable::Enumerator::Lazy

(1..10).lazy.map { _1 * 2 } => { first:, count: }
p first  # => 2
p count  # => 10

"Homu" in { downcase:, upcase: }
# => false

NOTE: Classes with #deconstruct_keys or #respond_to? defined will not work with using PatternMatchable.

require "pattern_matchable"

class X
  def respond_to?(...)
    super
  end
end

using PatternMatchable

# NoMatchingPatternKeyError
case { name: "homu", age: 14 }
in { first:, count: }
else
end


# NoMatchingPatternKeyError
case X.new
in { __id__: }
else
end

For example, ActiveRecord::Base. In this case, you must use using PatternMatchable X.

require "pattern_matchable"

class X
  def respond_to?(...)
    super
  end
end

using PatternMatchable Hash
using PatternMatchable X

case { name: "homu", age: 14 }
in { first:, count: }
  pp "ok: #{first}: #{count}"
  # => "ok: [:name, \"homu\"]: 2"
else
end


case X.new
in { __id__: }
  pp "ok: #{__id__}"
  # => "ok: 880"
else
end

Development

After checking out the repo, run bin/setup to install dependencies. Then, run rake spec to run the tests. You can also run bin/console for an interactive prompt that will allow you to experiment.

To install this gem onto your local machine, run bundle exec rake install. To release a new version, update the version number in version.rb, and then run bundle exec rake release, which will create a git tag for the version, push git commits and tags, and push the .gem file to rubygems.org.

Contributing

Bug reports and pull requests are welcome on GitHub at https://github.com/osyo-manga/pattern_matchable.