indexing
	description: "[
		Objects representing delayed calls to a function,
		with some arguments possibly still open.
		
		Note: Features are the same as those of ROUTINE,
			with apply made effective, and the addition
			of last_result and item.
	]"
	legal: "See notice at end of class."
	status: "See notice at end of class."
	date: "$Date: 2006-08-21 12:36:06 -0700 (Mon, 21 Aug 2006) $"
	revision: "$Revision: 62818 $"

class interface
	FUNCTION [BASE_TYPE, OPEN_ARGS -> TUPLE create default_create end, RESULT_TYPE]

create 
	default_create
			-- Process instances of classes with no creation clause.
			-- (Default: do nothing.)
			-- (from ANY)

feature -- Initialization

	adapt (other: like Current)
			-- Initialize from `other'.
			-- Useful in descendants.
			-- (from ROUTINE)
		require -- from ROUTINE
			other_exists: other /= Void
			conforming: conforms_to (other)
	
feature -- Access

	apply
			-- Call function with operands as last set.
		require -- from ROUTINE
			valid_operands: valid_operands (operands)

	call (args: OPEN_ARGS)
		require -- from ROUTINE
			valid_operands: valid_operands (args)

	empty_operands: OPEN_ARGS
			-- Empty tuple matching open operands
			-- (from ROUTINE)
		ensure -- from ROUTINE
			empty_operands_not_void: Result /= Void

	generating_type: STRING_8
			-- Name of current object's generating type
			-- (type of which it is a direct instance)
			-- (from ANY)

	generator: STRING_8
			-- Name of current object's generating class
			-- (base class of the type of which it is a direct instance)
			-- (from ANY)

	hash_code: INTEGER_32
			-- Hash code value.
			-- (from ROUTINE)
		ensure -- from HASHABLE
			good_hash_value: Result >= 0

	item (args: OPEN_ARGS): RESULT_TYPE
			-- Result of calling function with `args' as operands.
		require
			valid_operands: valid_operands (args)

	last_result: RESULT_TYPE
			-- Result of last call, if any.

	frozen operands: OPEN_ARGS
			-- (from ROUTINE)

	postcondition (args: like operands): BOOLEAN
			-- Does current state satisfy routine's
			-- postcondition for `args'?
			-- (from ROUTINE)

	precondition (args: like operands): BOOLEAN
			-- Do `args' satisfy routine's precondition
			-- in current state?
			-- (from ROUTINE)

	target: ANY
			-- Target of call.
			-- (from ROUTINE)
	
feature -- Measurement

	open_count: INTEGER_32
			-- Number of open operands.
			-- (from ROUTINE)
	
feature -- Comparison

	frozen deep_equal (some: ANY; other: like arg #1): BOOLEAN
			-- Are `some' and `other' either both void
			-- or attached to isomorphic object structures?
			-- (from ANY)
		ensure -- from ANY
			shallow_implies_deep: standard_equal (some, other) implies Result
			both_or_none_void: (some = Void) implies (Result = (other = Void))
			same_type: (Result and (some /= Void)) implies some.same_type (other)
			symmetric: Result implies deep_equal (other, some)

	frozen equal (some: ANY; other: like arg #1): BOOLEAN
			-- Are `some' and `other' either both void or attached
			-- to objects considered equal?
			-- (from ANY)
		ensure -- from ANY
			definition: Result = (some = Void and other = Void) or else ((some /= Void and other /= Void) and then some.is_equal (other))

	is_equal (other: like Current): BOOLEAN
			-- Is associated function the same as the one
			-- associated with `other'?
		require -- from ANY
			other_not_void: other /= Void
		ensure -- from ANY
			symmetric: Result implies other.is_equal (Current)
			consistent: standard_is_equal (other) implies Result

	frozen standard_equal (some: ANY; other: like arg #1): BOOLEAN
			-- Are `some' and `other' either both void or attached to
			-- field-by-field identical objects of the same type?
			-- Always uses default object comparison criterion.
			-- (from ANY)
		ensure -- from ANY
			definition: Result = (some = Void and other = Void) or else ((some /= Void and other /= Void) and then some.standard_is_equal (other))

	frozen standard_is_equal (other: like Current): BOOLEAN
			-- Is `other' attached to an object of the same type
			-- as current object, and field-by-field identical to it?
			-- (from ANY)
		require -- from ANY
			other_not_void: other /= Void
		ensure -- from ANY
			same_type: Result implies same_type (other)
			symmetric: Result implies other.standard_is_equal (Current)
	
feature -- Status report

	callable: BOOLEAN is True
			-- Can routine be called on current object?
			-- (from ROUTINE)

	conforms_to (other: ANY): BOOLEAN
			-- Does type of current object conform to type
			-- of `other' (as per Eiffel: The Language, chapter 13)?
			-- (from ANY)
		require -- from ANY
			other_not_void: other /= Void

	is_hashable: BOOLEAN
			-- May current object be hashed?
			-- (True if it is not its type's default.)
			-- (from HASHABLE)
		ensure -- from HASHABLE
			ok_if_not_default: Result implies (Current /= default)

	same_type (other: ANY): BOOLEAN
			-- Is type of current object identical to type of `other'?
			-- (from ANY)
		require -- from ANY
			other_not_void: other /= Void
		ensure -- from ANY
			definition: Result = (conforms_to (other) and other.conforms_to (Current))

	valid_operands (args: OPEN_ARGS): BOOLEAN
			-- Are `args' valid operands for this routine?
			-- (from ROUTINE)

	valid_target (args: TUPLE): BOOLEAN
			-- Is the first element of tuple `args' a valid target
			-- (from ROUTINE)
	
feature -- Removal

	clear_last_result
			-- Reset content of last_result to its default value
	
feature -- Duplication

	copy (other: like Current)
			-- Use same function as `other'.
		require -- from ANY
			other_not_void: other /= Void
			type_identity: same_type (other)
		ensure -- from ANY
			is_equal: is_equal (other)
		ensure then -- from ROUTINE
			same_call_status: other.callable implies callable

	frozen deep_copy (other: like Current)
			-- Effect equivalent to that of:
			--		copy (`other' . deep_twin)
			-- (from ANY)
		require -- from ANY
			other_not_void: other /= Void
		ensure -- from ANY
			deep_equal: deep_equal (Current, other)

	frozen deep_twin: like Current
			-- New object structure recursively duplicated from Current.
			-- (from ANY)
		ensure -- from ANY
			deep_equal: deep_equal (Current, Result)

	frozen standard_copy (other: like Current)
			-- Copy every field of `other' onto corresponding field
			-- of current object.
			-- (from ANY)
		require -- from ANY
			other_not_void: other /= Void
			type_identity: same_type (other)
		ensure -- from ANY
			is_standard_equal: standard_is_equal (other)

	frozen standard_twin: like Current
			-- New object field-by-field identical to `other'.
			-- Always uses default copying semantics.
			-- (from ANY)
		ensure -- from ANY
			standard_twin_not_void: Result /= Void
			equal: standard_equal (Result, Current)

	frozen twin: like Current
			-- New object equal to `Current'
			-- twin calls copy; to change copying/twining semantics, redefine copy.
			-- (from ANY)
		ensure -- from ANY
			twin_not_void: Result /= Void
			is_equal: Result.is_equal (Current)
	
feature -- Basic operations

	frozen default: like Current
			-- Default value of object's type
			-- (from ANY)

	frozen default_pointer: POINTER
			-- Default value of type `POINTER'
			-- (Avoid the need to write `p'.default for
			-- some `p' of type `POINTER'.)
			-- (from ANY)

	default_rescue
			-- Process exception for routines with no Rescue clause.
			-- (Default: do nothing.)
			-- (from ANY)

	frozen do_nothing
			-- Execute a null action.
			-- (from ANY)
	
feature -- Output

	io: STD_FILES
			-- Handle to standard file setup
			-- (from ANY)

	out: STRING_8
			-- New string containing terse printable representation
			-- of current object
			-- Was declared in ANY as synonym of tagged_out.
			-- (from ANY)

	print (some: ANY)
			-- Write terse external representation of `some'
			-- on standard output.
			-- (from ANY)

	frozen tagged_out: STRING_8
			-- New string containing terse printable representation
			-- of current object
			-- Was declared in ANY as synonym of out.
			-- (from ANY)
	
feature -- Platform

	operating_environment: OPERATING_ENVIRONMENT
			-- Objects available from the operating system
			-- (from ANY)
	
feature -- Settings

	frozen set_operands (args: OPEN_ARGS)
			-- Use `args' as operands for next call.
			-- (from ROUTINE)
		require -- from ROUTINE
			valid_operands: valid_operands (args)
		ensure -- from ROUTINE
			operands_set: (operands /= Void implies equal (operands, args)) or (operands = Void implies (args = Void or else args.is_empty))
	
invariant
		-- from ROUTINE
	callable: callable

		-- from ANY
	reflexive_equality: standard_is_equal (Current)
	reflexive_conformance: conforms_to (Current)

indexing
	library: "EiffelBase: Library of reusable components for Eiffel."
	copyright: "Copyright (c) 1984-2006, Eiffel Software and others"
	license: "Eiffel Forum License v2 (see http://www.eiffel.com/licensing/forum.txt)"
	source: "[
		Eiffel Software
		356 Storke Road, Goleta, CA 93117 USA
		Telephone 805-685-1006, Fax 805-685-6869
		Website http://www.eiffel.com
		Customer support http://support.eiffel.com
	]"

end -- class FUNCTION