Module: Constant::Import

Defined in:
lib/constant/import.rb,
lib/constant/import/macro.rb

Class Method Summary collapse

Class Method Details

.call(origin_constant, destination_constant, only: nil, except: nil, override_ancestor: nil, **kwargs) ⇒ Object



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# File 'lib/constant/import.rb', line 19

def self.call(origin_constant, destination_constant, only: nil, except: nil, override_ancestor: nil, **kwargs)
  override_ancestor ||= false

  if not destination_constant.is_a?(::Module)
    destination_constant = destination_constant.class
  end

  alias_name = kwargs[:alias]

  if alias_name.nil? && destination_constant.ancestors.include?(origin_constant)
    raise Constant::Error, "#{destination_constant} already includes #{origin_constant}"
  end

  target = destination_constant

  if not alias_name.nil?
    target = Define.(alias_name, destination_constant)
  end

  inherit = false

  import_constant_names = origin_constant.constants(inherit)

  only_constant_names = Array(only)
  only_constant_names = only_constant_names.map { |only_constant_name| only_constant_name.to_sym }

  except_constant_names = Array(except)
  except_constant_names = except_constant_names.map { |except_constant_name| except_constant_name.to_sym }

  conflicting_constant_names = only_constant_names & except_constant_names

  if conflicting_constant_names.any?
    conflicting_constant_name = conflicting_constant_names.first
    raise Constant::Error, "#{conflicting_constant_name} is named in both only: and except:"
  end

  if only_constant_names.any?
    undefined_constant_names = only_constant_names - import_constant_names

    if undefined_constant_names.any?
      undefined_constant_name = undefined_constant_names.first
      raise Constant::Error, "#{undefined_constant_name} is not defined on #{origin_constant}"
    end

    import_constant_names = import_constant_names & only_constant_names
  end

  import_constant_names = import_constant_names - except_constant_names

  if override_ancestor
    collision_constants = [target]
  else
    collision_constants = target.ancestors
  end

  import_constant_names.each do |import_constant_name|
    defining_constant = collision_constants.find do |collision_constant|
      collision_constant.const_defined?(import_constant_name, false)
    end

    if defining_constant.nil?
      next
    end

    if defining_constant.equal?(target)
      raise Constant::Error, "#{import_constant_name} is already defined on #{target} (imported from #{origin_constant})"
    end

    raise Constant::Error, "#{import_constant_name} is inherited by #{target} from #{defining_constant} (imported from #{origin_constant})"
  end

  imported_constants = import_constant_names.map do |import_constant_name|
    import_constant = origin_constant.const_get(import_constant_name, inherit)
    target.const_set(import_constant_name, import_constant)
    import_constant
  end

  imported_constants
end

.included(base) ⇒ Object



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# File 'lib/constant/import.rb', line 3

def self.included(base)
  if base.equal?(::Object)
    raise Constant::Error, "Constant::Import cannot be included at the top level, where the destination is Object. Activate the refinement instead: using Constant::Import"
  end

  base.extend(Macro)
end