ExpressionStorage

Store objects either as references (real objects) or as copy (expression templates). More...

Classes
struct	Dune::ACFem::ExpressionReferenceStorage< SomeThing >
	Store things as reference, serves as default implementation for the ExpressionStorage class. More...
struct	Dune::ACFem::ExpressionCopyStorage< SomeThing >
	Store things as copy, serves as default implementation for the ExpressionStorage class. More...
struct	Dune::ACFem::ExpressionStorage< SomeThing >
	An ExpressionStorage object stores either a copy or a reference of an object. More...

Detailed Description

Store objects either as references (real objects) or as copy (expression templates).

Expression templates are nice-to-have, but kind of dangerous in that one can easily construct references to temporary values. We try to cope with this problem by defining a ExpressionStorage object which holds a copy for expressions and a reference for real objects. For example, one does not want to copy a DiscreteFunction and the associated DoF storage when forming expressions, but one wants to copy the abstract PlusOperation class which models forming of a sum of such functions