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Ada

Language type:

O - Object-oriented

Description:

Ada is a block-structured language with many object-oriented programming features. It was originally designed for the US Dept. of Defense, and was intended to support large-scale programming and promote software reliability. Some of Ada's features include: nested procedures, nested packages, strong typing, multi-tasking, generics, exception handling, and abstract data types.
Primitive data types supported by Ada include a variety of numeric types, booleans, characters, references, and enumerated symbols. Arrays, records (structures), and strings are Ada's composite types. With its emphasis on program safety, it is not surprising that Ada is a strongly typed language: all data elements must be declared as storing a particular type or subtype, and type enforcement is strictly applied both within and between modules.
Ada supports a full complement of sequential control structures, as well as comprehensive exception handling.
Ada is very strictly standardized and well documented as a language. Ada compilers undergo stringent validation with an official test suite. At least one free Ada compiler and several good commercial ones are available.
Ada was named in honor of Lady Ada Lovelace (1815-1852), a friend and confidante of Charles Babbage.
Ada was initially standardized in 1983, and was superseded by a new standard in 1995. These two versions are now known as Ada 83 and Ada 95.

Origin:

Jean Ichibah et al, 1978-1983.

See Also:

Pascal    Algol    Modula-2    Jovial    CMS-2    Java   

Remarks:

Ada is a fairly complex language. It has a conventional but very rich Pascal-like syntax, with many specialized features. The best aspects of Ada are its support for generics (templates), its support for task synchronization, and its very good exception handling. Its worst features are its complex syntax, and the poor performance of the code generated by most early compilers. (by the late 1980s, compilers had improved, and modern Ada compilers generate code as fast or ever faster than that emitted from C or Fortran compilers). Note that Ada's semantics include range checking on all integer types, and bounds checking on all arrays; these program safety constraints slowed down early compilers (later ones got better at it, and also added support for compiler directives and pragmas that disabled certain checks in final release code).
Ada compilers tend to be very very strict, but if you ever got your program to compile you could be pretty sure it would at least do something comprehensible (unlike, for example, C).
Originally, Ada was designated as the ONLY language to be used for US DoD software development. This policy never really caught on, and by 1997 the rule was rescinded. Basically, the Defense Information Systems Agency (DISA) realized that even a language as painstakingly designed as Ada could not be a panacea.

Links:

AdaPower.com

Ada resource page in Switzerland

ACM SIGADA

Ada Core Technologies

Ada at DDC-I

Date:

Last updated 1/8/03

Sample code:

-- simple programming with floating-point #s
with Ada.Float_Text_IO;
use Ada.Float_Text_IO;
procedure Think is
   A, B : Float := 0.0; -- A and B initially zero; note the period.
   I, J : Integer := 1;
begin
   A := B * 7.0;
   I := J * 3;
   B := Float(I) / A;
   Put(B);
end Think;

Descriptions in this dictionary are ©1997-99 Neal Ziring. Some examples copyright of their respective authors. Some technologies and languages are trademarked. Permission to copy descriptions is granted as long as authorship credit is preserved.

Comments on this dictionary, corrections and suggestions, are all welcome. Please use email, the address is ziring@home.com