* @brief The DebugDelete class is a deleter functor using delete */

* @brief interface class to manage the Query_base inheritance hierachy */

forward declaration needed for friend declaration in StrBlob

forward declaration needed for friend declaration in StrBlob

forward declaration needed for friend declaration in StrBlob

unchanged from ch14 except for added friend declaration for hash.

for ex17.6 return a struct that holds an index of a store and iterators into that store's vector

* @brief The AndQuery class * *The & operator generates a AndQuery, which held by a Query, */

a basket of objects from Quote hierachy, using smart pointers.

* @brief The BinaryQuery class *An abstract class holds data needed by the query types that operate on two operands */

* @brief The BinaryQuery class *An abstract class holds data needed by the query types that operate on two operands */