Topic: data type by name or tags

topics > computer science > data > Group: data type

data type as a set of variables
data type by lexical constraints
database schema
naming conventions
object-oriented data types
structural equivalence vs. name equivalence of data types
XML data type


A data type may be a name or tag. All objects with the same name have the same type.

A domain is a named type for a database column. Domains may have the same physical representation. They specify the relationships between tables. For example a foreign key will belong to the same domain as the corresponding primary key.

Named types have inexpensive identity tests. The name typically refers to metadata about the type.

The name of a variable may indicate its type, typically by prefix. In object-oriented programming, the name may indicate the type of the name (e.g., this name is a pointer to a function). (cbb 6/06)

Subtopic: named type up

Quote: use named types for fine-grained types implemented by a program type; e.g., different kinds of strings
Quote: Pegasus types have unique names and represent collections of objects that share characteristics; interrelated by a DAG (multiple inheritance) [»ahmeR12_1991]
Quote: add type safety to Dylan macros by assigning nonterminal result types to metamorph parameters [»brabC1_2002]
Quote: a type is a subtype if every value matches the base type; because of named element typing, verify by regular expressions [»simeJ1_2003]
QuoteRef: cbb_1973 ;;5/7/79 so a type is simply a name

Subtopic: domain type up

Quote: a database column is a particular use of a domain; named to convey intended meaning without position or nextness [»coddEF_1990]
Quote: a domain distinguishes values of the same basic data type with a range and optional ordering [»coddEF_1990]
Quote: a domain or scalar data type is a named set of scalar values; name equivalence [»dateCJ_1998]
Quote: domains are the glue that holds a relational database together; shared descriptions; domain integrity, operators, and features
Quote: Improv items can be assigned a type category (a one-word description); appear on tiles near the row or column [»yageT10_1990]
Quote: instantly get a new view of a spreadsheet by moving the Systems Category tile from rows to columns; makes comparisons between systems easy [»yageT10_1990]

Subtopic: value vs. reference up

Quote: values may be members of many types, but Modula-3 objects and traced reference values have an allocated type that is tested by TYPECASE

Subtopic: object type up

Quote: the type of an object (simple, symbol, etc) is stored with the object [»kentW_1978]
Quote: typing by has-type relationship to objects of type TYPE [»kentW_1978]
Quote: the message/object model explicitly maintains the type of an object and the operators for a class; no need for memorization [»coxBJ7_1983]
Quote: Smalltalk objects are typed by their class [»shocJF9_1979]

Subtopic: type brand or trademark up

Quote: a reference type may be branded with a unique text constant; useful for subtyping and persistent data storage [»cardL_1991]
Quote: a brand can appear only once in a program; prevents access from a typecase to the representation of a branded, opaque type [»nelsG_1991]
Quote: in a form or class can declare a trademark for an object or value which can be detected but not modified [»maclBJ12_1983]
Quote: can restrict a type to those objects or values which carry a trademark [»maclBJ12_1983]

Subtopic: type as part of name, type tag, syntactic typing up

Quote: for type tags use two or three characters; may be random, must correspond to types [»simoC8_1991]
Quote: for syntactic typing just need 1 type per identifier; two types per id may balance lookup vs. number of procedures [»cbb_1980, OK]
Quote: include type indicator with literals [»cbb_1980, OK]
Quote: each variable has a prefix to identify data type and scalar vs. aggregate [»browRE7_1976]
QuoteRef: wileDS11_1973 ;;29 basic types (indicated by letter) signed integer, character, sequence, empty (nil) and string (sequence of characters)
QuoteRef: bennRK6_1968 ;;3-8 allows symbol prefixes to indicate default type (eg fortran's i2)

Subtopic: type test up

Quote: use TYPECASE to test the referent type of any traced object [»cardL_1991]

Subtopic: class loader up

Quote: Java separates data and implementation; data contains type tags that identify appropriate implementations, e.g., for downloading [»goslJ6_1997]
Quote: class loaders in Java locate an implementation for a class by its textual name; e.g., locate a handler for a new MIME type by its name [»goslJ6_1997]

Related Topics up

Topic: data type as a set of variables (11 items)
Topic: data type by lexical constraints (15 items)
Topic: database schema (29 items)
Topic: naming conventions (8 items)
Topic: object-oriented data types (29 items)
Topic: structural equivalence vs. name equivalence of data types (30 items)
Topic: XML data type
(22 items)

Updated barber 2/06
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Thesa is a trademark of C. Bradford Barber.