Patterns for Encapsulating Class Trees Patterns for Encapsulating Class TreesBy: D. Riehle
Published in: PLoPD2
Pages: 87-104
Category: Creational, Structural
Summary: Encapsulation of class hierarchies behind their root classes.
Url: http://www.riehle.org/papers/1995/plop-1995-trading.html
Pages: 92-94
Clients of an encapsulated class tree need to retrieve classes from that tree. Have the clients create a specification for classes they are interested in. The client requests all classes from the class tree that meet the specification.
Pages: 94-95
An encapsulated class tree is of no use unless objects of its internal classes can be created. Clients only know the interface class and a property that unambiguously identifies the class they are interested in. The client of a class creates a specification that unambiguously identifies a single class, then requests a new instance of a class that fits the specification.
Category: Creational
Pages: 95-98
A class clause makes an atomic statement about a class property that is true or false. It is represented by an object and can be compared to other clauses. It provides a basis for class specifications and first-class representations of class semantics.
Pages: 98-99
Clients use specifications to retrieve classes from a class tree. A class specification is a formula from propositional calculus with clauses as its basic constituents. Clients build a specification by creating clauses and using them in a formula.
Category: Structural
Pages: 99-101
Provide a set of clause instances for each class. Each clause makes a statement about the class. The set of clauses represents the semantics of the class. A class can be matched against a specification, which is realized by comparing clauses and evaluating the formula.
Category: Structural