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Arc de Triomphe clipart (2486 bytes)Observer Library


Written by Ted Velkoff (velkoff@erols.com)

observer.zip (317,817 bytes)


Identification

This is the Observer Library, Version 1.0, an implementation of the observer design pattern as a library of reusable components in Eiffel.

Platform

The Observer Library was developed using ISE Eiffel 4.0, Professional Edition for Windows 95, with back-end C compilation performed by Microsoft Visual C++ 4.0.

Limitations

The Observer Library has only been tested on a Windows 95 platform. It uses "long" file names.

Installation

To install the Observer Library, unzip the file `observer.zip' in a directory on your system, for example, C:\OBSERVER. You may find it useful to define an environment variable for that directory. For instance, in your autoexec.bat file, include the line:

SET OBSERVER=C:\OBSERVER

After unzipping, this directory will contain two subdirectories: `documentation' and `source'.

Documentation

The `documentation' directory contains a User's Guide to the Observer Library. About a dozen pages long, it contains an overview of the Library, including a description of its purpose, features, and design, as well as discussions of design goals and interesting language issues. The User's Guide is provided in four different formats: Microsoft Word 7.0 (`observer.doc'), Microsoft Word 6.0 (`observer.msword60.doc'), Rich Text Format (`observer.rtf'), and plain ASCII text (`observer.txt'). The ASCII text version should be your last resort; the other formats contain diagrams in the Business Object Notation (BON) and other formatting that facilitate understanding.

Source Code

The source code of the Observer Library may be found in the directories under `source'. For overview and descriptions, refer to the User's Guide.

Examples

Some very simple examples of use of the Observer Library may be found in each of its five clusters. These examples may be found in the directories

$OBSERVER\source\observer\<cluster>\test

where <cluster> is the name of one of the library's clusters. Since the Observer Library was developed using ISE's Eiffel Bench, the system descriptions are given as LACE files called `Ace.ace'. Each Ace file assumes that the environment variable $OBSERVER has been defined. To compile and execute one of the test programs, you will either need to set this environment variable (as mentioned above), or replace the reference to $OBSERVER in each Ace file with the actual name of the directory where the library is located.


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