Algorithms in a Nutshell

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Chapter 3. Patterns and Domains.................................................................................................................................................

3

Patterns and Domains

We build software to solve problems. During the decades since the first

programmed computer printed answers to previously unapproachable prob-

lems—such as computing the 400,052,412,247thdigit ofπ—programmers have

written countless programs to solve numerous problems. Programmers spent

hours happily writing code to solve the problem at hand, while at the same time

others also were coding solutions to identical, or very similar, problems. There are

several reasons programmers create unique solutions rather than seeking an

existing solution. One reason, of course, is the tendency to believe that we can

always build a better mousetrap. Programming for many of us has the same

appeal that the game of chess has for chess aficionados. Some reasons are more

important than others when considering why programmers continue to write the

same solutions for problems from scratch:

• The programmer doesn’t realize that the problem has already been solved.
  We’ll look into this further when we discuss problem domains.


• Even if the programmer knows the problem has been solved in similar cases,
  it’s not clear that the existing code will actually fit the specific problem fac-
  ing the programmer.


• It’s not easy to find code that really solves the problem at hand or code that
  can be easily modified to solve that problem.

Patterns: A Communication Language

In the late 1980s, a few visionary software developers began looking for new ways

to communicate their designs with one another. Some of them happened upon a

work by Christopher Alexander, a professor of architecture at the University of

California, Berkeley, calledA Pattern Language: Towns, Buildings, Construction

(1977). In this seminal work, Alexander developed a theory for describing archi-

tectural design. In 1987, Kent Beck and Ward Cunningham, two well-known

leaders of the object-oriented paradigm, introduced the idea of applying design

Algorithms in a Nutshell
Algorithms in a Nutshell By Gary Pollice, George T. Heineman, Stanley Selkow ISBN:
9780596516246 Publisher: O'Reilly Media, Inc.

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