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# frozen_string_literal: true
require "set"
module Dry
module Core
# Define extensions that can be later enabled by the user.
#
# @example
#
# class Foo
# extend Dry::Core::Extensions
#
# register_extension(:bar) do
# def bar; :bar end
# end
# end
#
# Foo.new.bar # => NoMethodError
# Foo.load_extensions(:bar)
# Foo.new.bar # => :bar
#
module Extensions
# @api private
def self.extended(obj)
super
obj.instance_variable_set(:@__available_extensions__, {})
obj.instance_variable_set(:@__loaded_extensions__, Set.new)
end
# Register an extension
#
# @param [Symbol] name extension name
# @yield extension block. This block guaranteed not to be called more than once
def register_extension(name, &block)
@__available_extensions__[name] = block
end
# Whether an extension is available
#
# @param [Symbol] name extension name
# @return [Boolean] Extension availability
def available_extension?(name)
@__available_extensions__.key?(name)
end
# Enables specified extensions. Already enabled extensions remain untouched
#
# @param [Array<Symbol>] extensions list of extension names
def load_extensions(*extensions)
extensions.each do |ext|
block = @__available_extensions__.fetch(ext) do
raise ArgumentError, "Unknown extension: #{ext.inspect}"
end
unless @__loaded_extensions__.include?(ext)
block.call
@__loaded_extensions__ << ext
end
end
end
end
end
end
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