class EL_OBJECT_SCOPE

(source code)

Client examples: GENERAL_TEST_SET

use_temporary_object
   do
      if attached temporary_scope as scope then
      -- do stuff
         scope.revert
      end
   end

temporary_scope: EL_OBJECT_SCOPE [MY_CLASS]
   do
      create Result.make (Standard_object, Temporary_object)
   end

Standard_object: MY_CLASS
   once
      create Result.make
   end

note
	description: "[
		Defines a scope in which the contents of a once object are temporarily replaced by the contents
		of another object of the same type using the `standard_copy' routine of class **ANY**.
	]"
	instructions: "[
		Usage Pattern:
		
			use_temporary_object
				do
					if attached temporary_scope as scope then
					-- do stuff
						scope.revert
					end
				end

			temporary_scope: EL_OBJECT_SCOPE [MY_CLASS]
				do
					create Result.make (Standard_object, Temporary_object)
				end
		
			Standard_object: MY_CLASS
				once
					create Result.make
				end

	]"

	author: "Finnian Reilly"
	copyright: "Copyright (c) 2001-2022 Finnian Reilly"
	contact: "finnian at eiffel hyphen loop dot com"

	license: "MIT license (See: en.wikipedia.org/wiki/MIT_License)"
	date: "2024-12-15 10:14:03 GMT (Sunday 15th December 2024)"
	revision: "2"

class
	EL_OBJECT_SCOPE [G -> ANY create default_create end]

create
	make

feature {NONE} -- Initialization

	make (a_once_object, scope_object: G)
		require
			same_type: a_once_object.same_type (scope_object)
		do
			once_object := a_once_object
			create once_copy
			once_copy.standard_copy (a_once_object)
			a_once_object.standard_copy (scope_object)
		end

feature -- Basic operations

	exit
		-- exit scope reverting `once_object' back to it's original state
		do
			once_object.standard_copy (once_copy)
		end

feature {NONE} -- Internal attributes

	once_object: G

	once_copy: G

end