Operator Names

This page has been created for the extention of Boost.TypeTraits by operator traits to ease an overview over existing naming of operators in the standards and boost libraries. The purpose of the page is to collect differences and support convergence.

Column	Comment
type_traits	boost::type_traits naming as proposed by Frédèric Bron.
MPU	Most Unifying Proposal
std	= : Equal naming in the standard
	?= : Standard naming not unique. One variant is equal.
proto	= : Equal naming in boost::proto
	*_p : Partial equality except for a prefix or postfix
operator	Corresponding naming of concepts from boost::operator

The names in column MPU are trying to minimize the differences between and so maximize the consistency. The naming from Boost.Proto is found in other boost libraries, e.g. accumulator.

	type_traits	MUP	std	proto	boost::operator
==	equal_to	equal_to	=	=	equality_comparable
!=	not_equal_to	not_equal_to	=	=
<	less	less	=	=	less_than_comparable
<=	less_equal	less_equal	=	=
>	greater	greater	=	=
>=	greater_equal	greater_equal	=	=
+	plus	plus	=	=	addable
-	minus	minus	=	=	subtractable
*	multiplies	multiplies	=	=	multipliable
/	divides	divides	=	=	dividable
%	modulus	modulus	=	=	modable
+=	plus_equal	plus_assign		*_assign
-=	minus_equal	minus_assign		*_assign
*=	multiplies_equal	multiplies_assign		*_assign
/=	divides_equal	divides_assign		*_assign
%=	modulus_equal	modulus_assign		*_assign
&&	logical_and	logical_and	?=	=
||	logical_or	logical_or	?=	=
&	bit_and	bit_and	?=	bitwise_*	andable
|	bit_or	bit_or	?=	bitwise_*	orable
^	bit_xor	bit_xor	?=	bitwise_*	xorable
<<	left_shift	left_shift		shift_left	left_shiftable
>>	right_shift	right_shift		shift_right	right_shiftable
&=	bit_and_equal	bit_and_assign	and_eq	bitwise_and_assign
|=	bit_or_equal	bit_or_assign	or_eq	bitwise_or_assign
^=	bit_xor_equal	bit_xor_assign	xor_eq	bitwise_xor_assign
<<=	left_shift_equal	left_shift_assign		shift_left_assign
>>=	right_shift_equal	right_shift_assign		shift_right_assign
++	prefix_increment	pre_increment	advance	pre_inc	incrementable
--	prefix_decrement	pre_decrement		pre_dec	decrementable
+	unary_plus	unary_plus		=
-	unary_minus	negate	negate	negate
!	logical_not	logical_not	?=	logical_not
~	complement	complement	compl	complement
*	dereference	dereference		dereference
++	postfix_increment	post_increment		post_inc
--	postfix_decrement	post_decrement		post_dec

There are some conflicts that have been solved under these rationals:

o=	op_equal vs. op_assign	proto and other boost::libs agree on op_assign. We can better conceptify to OpAssignable
	bit vs. bitwise	bitwise seems to be more "natural" but some naming in the standard prefers bit_ prefix
<< >>	shift_xxx or xxx_shift	goes to xxx_shift, because we can conceptify to xxx_shiftable more nicely.
++ --	pre/postfix vs. pre/post	goes to pre_in/decrement post_in/decrement. Seems simpler and more natural.

A higher naming consitency could be reached, if the standard was changed for 3 names:

// 20.8.7, bitwise operations:
template <class T> struct bit_and;
template <class T> struct bit_or;
template <class T> struct bit_xor;

In this case all the bit prefixes were replaced by bitwise.