Boost
C++ Libraries
...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::context::callable_context::eval
// In header: <boost/proto/context/callable.hpp>
template<typename Expr, typename ThisContext = Context>
struct eval : see-below {
};
A BinaryFunction that accepts an Expr and a
Context, and either fans out the expression and passes
it to the context, or else hands off the expression to DefaultCtx.
If Context is a PolymorphicFunctionObject
such that it can be invoked with the tag and children of Expr, as
ctx(typename Expr::proto_tag(), child_c<0>(expr),... child_c,
then eval inherits from
proto::context::callable_eval.
Otherwise, eval inherits from
DefaultCtx::eval.