...one of the most highly
regarded and expertly designed C++ library projects in the
world.
— Herb Sutter and Andrei
Alexandrescu, C++
Coding Standards
BOOST_PROTO_BASIC_EXTENDS — For creating expression wrappers that add members to a Proto expression template, like
proto::extends<>
,
but while retaining POD-ness of the expression wrapper.
// In header: <boost/proto/extends.hpp>
BOOST_PROTO_BASIC_EXTENDS(Expr, Derived, Domain)
BOOST_PROTO_BASIC_EXTENDS()
adds the basic typedefs, member functions, and
data members necessary to make a struct a valid Proto expression extension. It does not
add any constructors, virtual functions or access control blocks that would render the containing
struct non-POD.
Expr
is the Proto expression that the enclosing struct extends.
Derived
is the type of the enclosing struct.
Domain
is the Proto domain to which this expression extension belongs.
(See proto::domain<>
.)
BOOST_PROTO_BASIC_EXTENDS()
adds to its enclosing struct
exactly one data member of type Expr
.
Example:
template< class Expr > struct my_expr; struct my_domain : proto::domain< proto::pod_generator< my_expr > > {}; template< class Expr > struct my_expr { // OK, this makes my_expr<> a valid Proto expression extension. // my_expr<> does /not/ have overloaded assignment, subscript, // and function call operators that build expression templates, however. BOOST_PROTO_BASIC_EXTENDS(Expr, my_expr, my_domain) }; // OK, my_expr<> is POD, so this is statically initialized: my_expr< proto::terminal<int>::type > const _1 = {{1}};
See also: