Ada

language (After Ada Lovelace) A Pascal-descended

language, designed by Jean Ichbiah's team at CII Honeywell

in 1979, made mandatory for Department of Defense software

projects by the Pentagon. The original language was

standardised as "Ada 83", the latest is "Ada 95".

Ada is a large, complex, block-structured language aimed

primarily at embedded applications. It has facilities for

real-time response, concurrency, hardware access and

reliable run-time error handling. In support of large-scale

software engineering, it emphasises strong typing, dataabstraction and encapsulation. The type system uses nameequivalence and includes both subtypes and derived types.

Both fixed and floating-point numerical types are supported.

Control flow is fully bracketed: if-then-elsif-end if,

case-is-when-end case, loop-exit-end loop, goto. Subprogram

parameters are in, out, or inout. Variables imported from

other packages may be hidden or directly visible. Operators

may be overloaded and so may enumeration literals. There

are user-defined exceptions and exception handlers.

An Ada program consists of a set of packages encapsulating

data objects and their related operations. A package has a

separately compilable body and interface. Ada permits

generic packages and subroutines, possibly parametrised.

Ada support single inheritance, using "tagged types" which

are types that can be extended via inheritance.

Ada programming places a heavy emphasis on multitasking.

Tasks are synchronised by the rendezvous, in which a task

waits for one of its subroutines to be executed by another.

The conditional entry makes it possible for a task to test

whether an entry is ready. The selective wait waits for

either of two entries or waits for a limited time.

Ada is often criticised, especially for its size and

complexity, and this is attributed to its having been designed

by committee. In fact, both Ada 83 and Ada 95 were designed

by small design teams to be internally consistent and tightly

integrated. By contrast, two possible competitors, Fortran90 and C++ have both become products designed by large and

disparate volunteer committees.

See also Ada/Ed, Toy/Ada.

Home of the Brave Ada Programmers. Ada FAQs (hypertext), text only.

,

,

.

E-mail: [email protected].

Usenet newsgroup: news:comp.lang.ada.

An Ada grammar including a lex

scanner and yacc parser is available. E-mail:

[email protected].

ADA.EXTERNAL-TOOLSGRAM2.SRC'>Another yacc grammar and parser for Ada by Herman Fischer.

An LR parser and pretty-printer for Ada from NASA is

available from the Ada Software Repository.

Adamakegen generates makefiles for Ada programs.

["Reference Manual for the Ada Programming Language", ANSI/MIL

STD 1815A, US DoD (Jan 1983)]. Earlier draft versions

appeared in July 1980 and July 1982. ISO 1987.

[Jargon File]

(2000-08-12)