Topic: type hierarchy

topics > computer science > programming > object-oriented programming > Group: type inheritance

derived data types

hierarchical structures
inheritance of properties
non-hierarchical classification and multiple classification
object-oriented data types
object-oriented design
problems with type inheritance
restricted and extended types
type conversion
type inheritance as reuse


Type inheritance defines a type hierarchy. Subclasses of a type can be used wherever the type is used. (cbb 4/01)
Subtopic: root of type hierarchy up

Quote: every Smalltalk class, except Object, has a superclass [»xlrg8_1981]
Quote: 'void*' is the root of the tree of class conversions; it is used if no other function matches a "more derived" class [»stroB_1994]
Quote: Sketchpad is organized into a Universe of Variables, Holders, Constraints, and Types; the later includes Lines, Circles, and Pictures [»suthIE5_1963]

Subtopic: type hierarchy from base classes up

Quote: a node class belongs to a type hierarchy. It provides an interface and services. It relies on base classes [»stroB_1991]

Subtopic: clusters, library, namespace, taxonomy up

Quote: should gather object classes into clusters or libraries; limit cycles in the client relation to a cluster [»meyeB9_1990]
Quote: Eiffel's Data Structure Library defines a taxonomy for data structures by access method, traversing, and storage; e.g., CONTAINER class [»meyeB9_1990]

Subtopic: prototype inheritance up

Quote: prototype descriptions are related via hierarchies with different degrees of abstraction
Quote: Kevo uses family resemblance instead of explicitly sharing object representations [»taivA11_1997]

Subtopic: hierarchy as derived class up

Quote: use derived classes to express hierarchical relationships; i.e., commonality between classes

Subtopic: subtypes as entity type up

Quote: entities of a subtype of an entity type are necessarily entities of the parent type

Subtopic: single inheritance up

Quote: a entity type has a name, super type or symbol type [»kentW1_1984]
Quote: DELTA defines a hierarchy of objects; objects can not exist without their parent existing [»handP_1981]

Subtopic: class vs. instance up

Quote: there is no semantic difference between class and instance messages; distinction is for organization [»xlrg8_1981]
Quote: a Smalltalk metaclass describes a class; a class's instance variables describes an instance; 'new' creates a new instance [»xlrg8_1981]

Subtopic: dynamic vs. static type up

Quote: an entity is declared with a static type and associated with a dynamic type at runtime; all dynamic types must be descendants

Subtopic: import, export up

Quote: Oberon's modules form an import/export hierarchy; no distinction between operating system and applications [»wirtN9_1989]

Subtopic: 'type' as a type up

Quote: the type 'type' is a type; it is an instance of itself

Subtopic: subtype implementation up

Quote: subtype testing via PQ-trees; small footprint, constant time; originally used in constraint ordering

Related Topics up

Group: derived data types   (9 topics, 119 quotes)

Topic: hierarchical structures (46 items)
Topic: inheritance of properties (24 items)
Topic: namespace (19 items)
Topic: non-hierarchical classification and multiple classification (16 items)
Topic: object-oriented data types (29 items)
Topic: object-oriented design (30 items)
Topic: problems with type inheritance (20 items)
Topic: restricted and extended types (35 items)
Topic: taxonomy (16 items)
Topic: type conversion (33 items)
Topic: type inheritance as reuse
(27 items)

Updated barberCB 3/05
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