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- Language type:
Theta is an object-oriented language with
a sophisticated and
flexible type system, developed by
the MIT Programming Methodology Group.
Theta supports a fairly conventional set
of built-in data types and control
structures. Integers, reals, characters,
strings, booleans, and subroutine
references are all primitive types.
Composite types are parameterized (generic),
and include arrays, sequences, vectors,
records, and structs.
Control structures include conditional
and loop constructs, and simple
The parameterized type system of Theta is
very powerful, and allows a programmer to
cleanly define new abstract type
templates with desired properties.
Object classes in Theta are associated
with user-defined types: a type is
implemented by one or more classes.
Theta supports single inheritance for
classes; the programmer can restrict how
a class may be subclassed (like Java but
Theta uses a rooted type hierarchy: all
types are subtypes of "any"
(even built-ins like "int").
Routine types are also part of the
hierarchy, and the type rules are used
to enforce method call type conformance.
Types are decoupled from classes.
Theta supports separately compiled modules,
optionally supplying multiple implementations
for a particular type interface.
Memory management in Theta is dynamic
and automatic. Unreferenced objects
are reclaimed by a garbage collector.
The Thor database provides object persistence
for Theta objects.
As of early 1998, the MIT Theta implementation
was not available for download, possibly
because Theta is bound to Thor? The Theta
reference manual is available (link below).
Barbara Liskov et al, MIT, 1994.
- See Also:
Theta was developed to be the programming
language for Thor, a distributed transactional
OO database system. One of the goals
of the overall Thor project was to
study distributed object systems, and the
Theta language embodies features derived
from that research.
Descriptions in this dictionary are ©1997-99 Neal Ziring. Some
examples copyright of their respective authors. Some
technologies and languages are trademarked. Permission to
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Dictionary and script maintained by Neal Ziring, last major modifications 3/18/98. Most recent
additions to dictionary and master list, 1/00.