boost/more
1
0
Fork 0
mirror of https://github.com/boostorg/more.git synced 2025-04-21 17:50:17 +08:00
Code Issues Packages Projects Releases Wiki Activity

Remove the library reuse page, as it has been added to the new site. Refs

Browse Source 
[SVN r40988]
This commit is contained in:
Daniel James 2007-11-10 15:08:20 +00:00
parent 49923e9f6a
commit 889723c1a9
1 changed files with 0 additions and 75 deletions

75
library_reuse.htm
View File

@ -1,75 +0,0 @@
<!DOCTYPE html PUBLIC "-//W3C//DTD HTML 4.01 Transitional//EN">
<html>
<head>
<meta http-equiv="Content-Language" content="en-us">
<meta http-equiv="Content-Type" content="text/html; charset=windows-1252">
<meta name="GENERATOR" content="Microsoft FrontPage 5.0">
<meta name="ProgId" content="FrontPage.Editor.Document">
<title>Boost Library Reuse</title>
</head>
<body bgcolor="#FFFFFF" text="#000000">
<table border="1" bgcolor="#007F7F" cellpadding="2">
<tr>
<td bgcolor="#FFFFFF"><img src="../boost.png" alt="boost.png (6897 bytes)" width="277" height="86"></td>
<td><a href="../index.htm"><font face="Arial" color="#FFFFFF"><big>Home</big></font></a></td>
<td><a href="../libs/libraries.htm"><font face="Arial" color="#FFFFFF"><big>Libraries</big></font></a></td>
<td><a href="../people/people.htm"><font face="Arial" color="#FFFFFF"><big>People</big></font></a></td>
<td><a href="faq.htm"><font face="Arial" color="#FFFFFF"><big>FAQ</big></font></a></td>
<td><a href="index.htm"><font face="Arial" color="#FFFFFF"><big>More</big></font></a></td>
</tr>
</table>
&nbsp;
<h1>Boost Library reuse: cost versus benefit trade-offs</h1>
<p>A Boost library <b>should not</b> use libraries other than Boost or the C++
Standard Library.</p>
<p>A Boost library <b>should</b> use other Boost Libraries or the C++ Standard
Library, but only when the benefits outweigh the costs.&nbsp;</p>
<p>The benefits of using components from other libraries may include clearer,
more understandable code, reduced development and maintenance costs, and the
assurance which comes from reusing well-known and trusted building blocks.</p>
<p>The costs may include undesirable coupling between components, and added
compilation and runtime costs.&nbsp; If the interface to the additional
component is complex, using it may make code less readable, and thus actually
increase development and maintenance costs.</p>
<p>Negative effects of coupling become obvious when one library uses a second
library which uses a third, and so on. The worst form of coupling requires the
user understand each of the coupled libraries. Coupling may also reduce the
portability of a library - even in case when all used libraries are
self-sufficient (see example of questionable usage of &lt;iostream&gt; library
below).</p>
<p><b>Example where another boost component should certainly be used:</b>&nbsp;
boost::noncopyable (in <a href="../boost/utility.hpp">boost/utility.hpp</a>) has
considerable benefits; it simplifies code, improves readability, and signals
intent.&nbsp; Costs are low as coupling is limited;&nbsp; noncopyable itself
uses no other classes and its header includes only the lightweight headers
&lt;boost/config.hpp&gt; and &lt;cstddef&gt;.&nbsp; There are no runtime costs
at all. With costs so low and benefits so high, other boost libraries should use
boost::noncopyable when the need arises except in exceptional circumstances.</p>
<p><b>Example where a standard library component might possibly be used:</b>
Providing diagnostic output as a debugging aid can be a nice feature for a
library. Yet using Standard Library &lt;iostream&gt; can involves a lot of
additional cost, particularly if &lt;iostream&gt; is unlikely to be use
elsewhere in the application.&nbsp; In certain GUI or embedded applications,
coupling to &lt;iostream&gt; would be a disqualification.&nbsp;&nbsp;&nbsp;
Consider redesign of the boost library in question so that the user supplies the
diagnostic output mechanism.</p>
<p><b>Example where another boost component should not be used:</b>&nbsp; The
boost dir_it library has considerable coupling and runtime costs, not to mention
portability issues for unsupported operating systems.&nbsp; While completely
appropriate when directory iteration is required, it would not be reasonable for
another boost library to use dir_it just to check that a file is available
before opening.&nbsp; C++ Standard Library file open functionality does this at
lower cost.&nbsp; Don't use dir_it just for the sake of using a boost library.</p>
<hr>
<p>Revised <!--webbot bot="Timestamp" s-type="EDITED" s-format="%d %B %Y" startspan -->02 October 2003<!--webbot bot="Timestamp" endspan i-checksum="32277" --></p>
<p>© Copyright Beman Dawes 2000</p>
<p>Distributed under the Boost Software License, Version 1.0. (See
accompanying file <a href="../LICENSE_1_0.txt">LICENSE_1_0.txt</a> or copy
at <a href="http://www.boost.org/LICENSE_1_0.txt">http://www.boost.org/LICENSE_1_0.txt</a>)</p>
</body>
</html>