April 2000 Frame page

<body> <table border="0" cellpadding="6" cellspacing="0" width="735" height="518"> <tr> <td align="right" valign="top" width="206" height="1"> <p align="center"><img border="0" src="images/Accent03.gif" align="left" width="142" height="37"> </p> <p align="left"><b><font size="2">April 2000 - Vol. 1 No. 4</font></b></p> </td> <td valign="bottom" width="501" height="1"> <p align="center">  <a href="index.html" target="_top">[Home]</a> <a href="Newsletters.html" target="_top">[Up]</a> <a href="2000-05.html" target="_top">[Next]</a> <a href="2000-03.html" target="_top">[Previous]</a></td> </tr> <tr> <td valign="top" width="206" height="529" bgcolor="#FFFFCC"> <p><font size="2"> <a href="#TechTalk"><b>Tech Talk</b></a></font><font size="3"><br> </font><a href="#DesigningIterators"><font size="2">Designing C++ Iterators<br> </font></a><a href="#IteratorCategories">Iterator Categories<font size="2"><br> </font> </a><font size="2"><br> <a href="#Trends"><b>Trends</b></a></font> <font size="4"><br> </font><font size="2"><a href="#SD2000">SD'2000</a><br> <b><br> <a href="#WhatsHot">What's Hot, What's Not<br> </a></b><a href="#LostBoys">Lost Boys</a><a href="#WhisperProgStudio"><br> Whisper Programmer Studio<br> </a><a href="#VMWare">VMWare v2.0</a></font> </p> <p><font size="2"><a href="#Editorial"><b>Editorial</b></a></font> <font size="3"><br> </font><font size="2"><a href="#MyMistake">My Mistake + Apologies</a><a href="2000-04-Main.html#MyMistake"><br> </a><a href="#NameChange">Name Change<br> </a> </font> </p> </td> <td valign="top" height="529" bgcolor="#FFCC99" width="501"> <b> <h1><a name="TechTalk"><font color="#000000">Tech-Talk</font></a></h1> <h2><a name="DesigningIterators"><font face="Arial" color="#000000">Designing C++ Iterators</font></a></h2> </b><i><font SIZE="2"> <p>By Reg. Charney</p> </font></i> <p>If you plan to design a container class of objects, you often want to access each element of the container. Iterators can do this. Here is a simple recipe for creating iterators for your containers:</p> <blockquote> <ul> <li>Containers are classes that contain zero, one or more elements.</li> <li>An iterator is a class that can be used to access each member of its associated container.</li> <li>Iterators (I) are intimately associated with their container classes (C). Thus, iterators are defined as nested public classes (C::I) inside their related container classes.</li> <li>Due to C++ access rules, iterators and container classes are often mutual <font FACE="Courier New">friend</font> classes of each other.</li> <li>In C++, iterators are often treated as generalized pointers. The following operations are defined on iterators: <font FACE="Courier New">*(</font>dereference), <font FACE="Courier New">-></font>,<font FACE="Courier New"> ++</font>,<font FACE="Courier New"> ==</font>, !=, The copy, and assignment operators are also defined, if they make sense.</li> <li>There must be two container class member functions : <font FACE="Courier New">C::begin()</font> and <font FACE="Courier New">C::end() i</font>n each container class that has iterators, .</li> <li><font FACE="Courier New">C::end()</font> returns an iterator pointing “one past” the last element of the container. Often <font FACE="Courier New">C::end()</font> returns a default iterator. <font FACE="Courier New">C::begin()</font> returns an iterator pointing to the first element in the container. If the container is empty, <font FACE="Courier New">C::begin()</font> returns the value of <font FACE="Courier New">C::end().</font></li> </ul> </blockquote> <p>The <font FACE="Courier New">C::begin()</font> member function connects the <font FACE="Courier New">this </font>pointer for the container with each defined iterator.</p> <p>To save space below, many normal member functions have been omitted from this executable example.</p> <b><i> <h2><a name="IteratorCategories"><font FACE="Arial" color="#000000">Iterator Categories</font></a></h2> </i></b> <p>Iterators come in five categories, remembered using the acronym BRIEF: Bi-directional, Random, Input, Emit/output, and Forward.</p> <b><i> <h3><font FACE="Arial" color="#000000">Input iterators:</font></h3> </i></b><blockquote><b><i> </i></b> <ul> <li>One pass, forward only.</li> <li>Can’t be dereferenced, copied or assigned.</li> <li>No write access</li> <li>No lvalue, can be on the left hand side of an assignment</li> </ul> </blockquote> <b><i> <h3><font FACE="Arial" color="#000000">Emit/Output Iterators</font></h3> </i></b><blockquote><b><i> </i></b> <ul> <li>One pass, forward only.</li> <li>Dereferencing only on the left hand side of an assignment.</li> <li>No read access</li> <li>Usually only one output iterator instantiated at a time</li> </ul> </blockquote> <b><i> <h3><font FACE="Arial" color="#000000">Forward Iterators</font></h3> </i></b><blockquote><b><i> </i></b> <ul> <li>Can move forward.</li> <li>Iterator values can be stored and retrieved – can be dereferenced on left or right side of an assignment.</li> </ul> </blockquote> <b><i> <h3><font FACE="Arial" color="#000000">Bi-Directional Iterators</font></h3> </i></b><blockquote><b><i> </i></b> <ul> <li>Have all the attributes of Forward iterators, and can move backwards.</li> </ul> </blockquote> <b><i> <h3><font FACE="Arial" color="#000000">Random Iterators</font></h3> </i></b><blockquote><b><i> </i></b> <ul> <li>Have all attributes of Bi-Directional iterators plus are able to access entries in the container in any order. Member function <font FACE="Courier New">at()</font> and <font FACE="Courier New">operator[]</font> are defined.</li> </ul> </blockquote> <p>The container’s design solely determines the category of iterator. You can not impose an iterator or iterator category onto a container from the outside.</p> <p>Material for designing iterators can be found in <i>Designing Components with the C++ STL</i> by Ulrich Breymann, Addison-Wesley, ISBN 0-201-67488-2. And again, Nicolai M. Josuttis’s <i>The C++ Standard Template Library</i>, Addison-Wesley, ISBN 0-201-37926-0 is also an excellent source for examples and information on iterators.</p> <p><a href="Listings/2000-04-Listing01.html" target="_blank">Iterator Example</a></p> <h1><a name="Editorial" href="2000-02.html"><font color="#000000">Editorial</font></a></h1> <i> <p><font SIZE="2" FACE="Arial" color="#000000">By Reg. Charney</font></p> </i><b> <h2><font FACE="Arial" SIZE="4" color="#000000"><a name="MyMistake">My Mistake + Apologies</a></font></h2> </b> <p><font color="#000000">I have had a lot of fun designing, creating, and writing this newsletter. But in the last issue, I had gone too far and I was not serving you and for this I offer my apologies. Last month’s editorial comment was the largest part of the newsletter. It did not start out that way, but time and other factors got in the way. I also realized that in my first issue, I promised to be pithy, to the point and technically oriented. Again, that did not happen, except for the excellent technical article by Michael Ball on Compile-Time Template Calculations. Lastly, the technical content was almost buried on page three. All in all, not a good way to go.</font></p> <p><font color="#000000">So I am now going to make a commitment to you. One that is measurable and one that I can use as a benchmark. The editorial content of the newsletter will be limited to one column in this four-page format (i.e., 12% of the newsletter). Second, the technical articles are going to have pride of place. Each newsletter will start with technical material, not editorial, on page one. The editorial will not appear on page one unless really extraordinary circumstances dictate that it do so. Lastly, some form of the newsletter will appear on the web, hopefully, by the time you read this.</font></p> <p><font color="#000000">This newsletter is here to serve you, so let’s hear your feedback – good or bad . Please let us know how best to do this.</font></p> <b> <h2><font FACE="Arial" SIZE="4" color="#000000"><a name="NameChange">Name Change</a></font></h2> </b> <p>Recently, I have had some negative comments to the name ACCU’SiVe. It sounded too much like j’accuse – which some Frenchman, Victor Hugo, has already taken. We have received some suggestions, but want more. Starting with this issue, ACCU’SiVe has been renamed ACC++ent. However, if you have a better name, let us know.</p> <h1><font color="#000000"><a name="Trends">Trends</a></font></h1> <i><font SIZE="2"> <p>By Reg. Charney</p> </font></i><b> <h2><font SIZE="4" face="Arial"><a name="SD2000">SD’2000</a></font></h2> </b> <p><font color="#000000">The Software Development 2000 Conference in San Jose has just finished, so instead of doing job market statistics, I thought you might be interested in the changes over the last year in a number of show categories.</font></p> <p><font color="#000000">Measurement was by counting vendors and the categories that they represented. There were some changes in categories from 1999 to 2000. For example, no one advertises 3GLs any longer, while middleware is a new category in 2000. The only major positive change was that the number of vendors offering client/server solutions increased. Comparing categories is difficult because one can argue about material changes as opposed to buzzword changes.</font></p> <p><font color="#000000">Even though the numbers were smaller than last year, the courses offered were very good— especially the tutorials. I was also surprised by some of the exhibits, which I will discuss next.</font></p> <font SIZE="2"> <p align="center"><img border="0" src="images/2000-04-Fig01.gif" width="462" height="442"></p> <p align="center"><b>Figure #1</b></p> <p align="center"><img border="0" src="images/2000-04-Fig02.gif" width="458" height="294"></p> <p align="center"><b>Figure #2</b></p> </font><b><font COLOR="#000099"> <h1><a name="WhatsHot">What’s Hot and What’s Not</a></h1> </font><font FACE="Arial" COLOR="#000099"> <p><a name="LostBoys">Lost Boys</a></p> </font></b> <p><font color="#000000">This was the most visually impressive product I saw. Lost Boys’ multimedia C++ development environment is smooth, powerful and seems easy to use and program. It works on a whole range of machines, from old Pentiums to the latest speed demons, under Windows, Linux, BeOS and MacOS. They are from the Netherlands. Their demo of Anne Frank’s house is spectacular. You can find them at www.lostboys.com. Their website is also a treat.</font></p> <b><font FACE="Arial" COLOR="#000099"> <p><a name="WhisperProgStudio">Whisper Programmer Studio</a></p> </font></b> <p><font color="#000000">These U.K. folks have a very nice IDE that is platform independent. Their features match the most sophisticated ones on Windows. It is also compiler and tool independent. You can find them at www.wispertech.com.</font></p> <b><font FACE="Arial" COLOR="#000099"> <p><a name="VMWare">VMWare</a> v2.0</p> </font></b> <p><font color="#000000">Although not a new product, the improvements and features of this product make it an essential tool for developers. The ability to roll back changes and maintain reference platforms is wonderful. See them at www.vmware.com.</font></p> <h1> </h1> <p> </p> </td> </tr> </table> <p> </body>