February 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">February 2000 - Vol. 1 No. 2</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="2000-03.html" target="_top">[Next]</a> <a href="2000-01.html" target="_top">[Previous]</a></td> </tr> <tr> <td valign="top" width="206" height="529" bgcolor="#FFFFCC"> <p><font size="2"><a href="#Editorial"><b>Editorial</b></a></font><font size="3"><br> </font><font size="2"><a href="#Reviews">Reviews, Reviews, Reviews</a><br> <a href="#Immortality">Immortality and What's in a Name</a><br> <a href="#FormatChange">Format Change</a><br> <a href="#Thanks">Thanks to Computer Literacy</a><br> <br> <a href="#Trends"><b>Trends</b></a></font><font size="4"><br> </font><font size="2"><a href="#ChangeInTrends">Changes in Trends</a><br> <a href="#SVDifference">The Silicon Valley Difference</a><br> <b><br> <a href="#WhatsHot">What's Hot, What's Not</a></b><strong><br> </strong><a href="#ProgrammingLinux">Linux Programming</a><br> </font><font size="3"><br> </font><font size="2"><a href="#TechTalk"><b>Tech Talk<br> </b></a></font><font size="2"><a href="#Conversion">Conversion During Initialization<br> </a></font><font size="3"><a href="#SmartPointers"><font size="2">Smart Pointers in the C++ STL</font></a><font size="2"><br> </font></font></p> </td> <td valign="top" height="529" bgcolor="#FFCC99" width="501"> <h1><a name="Editorial">Editorial</a></h1> <h2><a name="Reviews">Reviews, Reviews, Reviews</a></h2> <p class="Byline-Contemporary"><i>By Reg. Charney, Editor</i></p> <p class="BodyText-Contemporary"><span style="layout-grid-mode:line">We have a love/hate relationship with reviews. While we all like reading or seeing movie reviews, we hate doing book reviews. And while code reviews are valuable, we are ambivalent about them because it might be our code that's reviewed and few of us like to be criticized. At the moment, the ACCU can't offer you movies, but we can offer you books and software to review. We can even offer guidelines on doing these reviews. What you need to do is add the active ingredient to this mix - your time and effort. And what do you get for doing this? I am glad you asked. <o:p> </o:p> </span></p> <p class="BodyText-Contemporary" style="margin-top:0in;margin-right:0in; margin-bottom:0in;margin-left:.25in;margin-bottom:.0001pt;text-indent:-.25in; line-height:normal;mso-list:l0 level1 lfo3;tab-stops:list .25in"><span style="font-family:Symbol;layout-grid-mode:line">·<span style="font:7.0pt "Times New Roman"">         </span></span><span style="layout-grid-mode:line">You get to see your name both in print and on the Web. <o:p> </o:p> </span></p> <p class="BodyText-Contemporary" style="margin-top:0in;margin-right:0in; margin-bottom:0in;margin-left:.25in;margin-bottom:.0001pt;text-indent:-.25in; line-height:normal;mso-list:l0 level1 lfo3;tab-stops:list .25in"><span style="font-family:Symbol;layout-grid-mode:line">·<span style="font:7.0pt "Times New Roman"">         </span></span><span style="layout-grid-mode:line">You get national and international exposure. <o:p> </o:p> </span></p> <p class="BodyText-Contemporary" style="margin-top:0in;margin-right:0in; margin-bottom:0in;margin-left:.25in;margin-bottom:.0001pt;text-indent:-.25in; line-height:normal;mso-list:l0 level1 lfo3;tab-stops:list .25in"><span style="font-family:Symbol;layout-grid-mode:line">·<span style="font:7.0pt "Times New Roman"">         </span></span><span style="layout-grid-mode:line">You get to develop a reputation as an expert on what you reviewed. <o:p> </o:p> </span></p> <p class="BodyText-Contemporary" style="margin-top:0in;margin-right:0in; margin-bottom:0in;margin-left:.25in;margin-bottom:.0001pt;text-indent:-.25in; line-height:normal;mso-list:l0 level1 lfo3;tab-stops:list .25in"><span style="font-family:Symbol;layout-grid-mode:line">·<span style="font:7.0pt "Times New Roman"">         </span></span><span style="layout-grid-mode:line">You get to keep, for free, what you review. If you where interested in the subject anyway, this is a painless way of getting it. (Remember, these books usually cost $30-$70 each and software often costs $50-$1,000.)<o:p> </o:p> </span></p> <p class="BodyText-Contemporary" style="margin-top:0in;margin-right:0in; margin-bottom:0in;margin-left:.25in;margin-bottom:.0001pt;text-indent:-.25in; line-height:normal;mso-list:l0 level1 lfo3;tab-stops:list .25in"><span style="font-family:Symbol;layout-grid-mode:line">·<span style="font:7.0pt "Times New Roman"">         </span></span><span style="layout-grid-mode:line">Active involvement in the ACCU will give you more leverage in getting: your next job, peer approval, and access to people, places and things.<o:p> </o:p> </span></p> <p class="BodyText-Contemporary"><span style="layout-grid-mode:line">And, of course, you get the proverbial pat on the back for bettering your fellow members and the programming world.<o:p> </o:p> </span></p> <span style="font-size:10.0pt;font-family:"Times New Roman";mso-fareast-font-family: "Times New Roman";mso-ansi-language:EN-US;mso-fareast-language:EN-US; mso-bidi-language:AR-SA;layout-grid-mode:line">What's in it for the ACCU and Open Source Software movement? Your </span><span style="layout-grid-mode:line">involvement makes us one the most active organizations in the world of computing. We will become a source and beacon for all professionals and those aspiring to improve their programming technical skills. Other organizations will want to work with us. We will be fulfilling our purpose with a vengeance.<o:p> </o:p> </span> <p class="BodyText-Contemporary"><span style="layout-grid-mode:line">So, review this opportunity and contact me. We have the books and software available. Our web site will list those by the time you see this issue of our newsletter.<o:p> </o:p> </span></p> <h2><a name="Immortality">Immortality and What's in a Name</a></h2> <p class="BodyText-Contemporary"><span style="layout-grid-mode:line">To quote Shakespeare, we are hoping that "A rose is still a rose by any other name". While ACCU'SiVe had a derivation (ACCU of Silicon Valley) and was pronounceable, it has no pizzazz nor is it meaningful to the uninitiated. Thus, we are looking for a catchier name. Current favorites include ACCUte, ACCUrate, and ACC<sup>++</sup>ent. Let us know which you prefer, or if you have a better name. There is a terrific prize worth what I paid for it to the winner, plus an honorable or dishonorable mention, as desired. And remember, your name will appear forever at the top of our newsletter - talk about immortality!<o:p> </o:p> </span></p> <h2><a name="FormatChange">Format Change</a></h2> <p class="BodyText-Contemporary"><span style="layout-grid-mode:line">To facilitate printing in one color, some changes have been made to the printed layout.<o:p> </o:p> </span></p> <h2><a name="Thanks">Thanks Computer Literacy</a></h2> <p class="BodyText-Contemporary"><span style="layout-grid-mode:line">Besides providing ACCU with meeting space, Computer Literacy is also sponsoring the printing of ACCU’SiVe. Thanks Computer Literacy – you’re great!</span> <h1><a name="Trends">Trends</a></h1> <p class="Byline-Contemporary"><i>By Reg. Charney</i></p> <h2><a name="ChangeInTrends">Change in Trends</a></h2> <p class="Heading2-Contemporary"><span style="font-family:"Times New Roman"; font-weight:normal">Last month we talked about the demand for various programming languages. This month’s column shows the<span style="mso-spacerun: yes">  </span>current demands in Figures #1 and #2, but I have also included the change in demand by language.</span></p> <p class="Heading2-Contemporary" align="center"><span style="font-size:10.0pt;font-family:"Times New Roman"; mso-fareast-font-family:"Times New Roman";mso-ansi-language:EN-US;mso-fareast-language: EN-US;mso-bidi-language:AR-SA"> <img src="images/2000-02-Fig01.gif" v:shapes="_x0000_i1025" width="339" height="249"> </span></p> <p class="Heading2-Contemporary" align="center"><b>Figure #1: Seven Month Demand Trend - Languages</b></p> <p class="Heading2-Contemporary" align="left"><span style="font-family:"Times New Roman"; font-weight:normal">The normalized demand for languages in Figure #2 shows that the demand for Java now slightly outstrips the demand for both C and C++.</span></p> <p class="Heading2-Contemporary" align="center"><span style="font-family:"Times New Roman"; font-weight:normal"><o:p> </o:p> <img src="images/2000-02-Fig02.gif" v:shapes="_x0000_i1025" width="358" height="239"></span></p> <p class="BodyText-Contemporary" align="center"><b>Figure #2: Normalized Demand by Languages</b></p> <p class="BodyText-Contemporary">Figure #3 shows the demand for C++, Java, and Perl has continued to accelerate while the demand for HTML and VB has declined in the last month.</p> <p class="BodyText-Contemporary" align="center"><span style="font-size:10.0pt;font-family:"Times New Roman"; mso-fareast-font-family:"Times New Roman";mso-ansi-language:EN-US;mso-fareast-language: EN-US;mso-bidi-language:AR-SA"> <img src="images/2000-02-Fig03.gif" v:shapes="_x0000_i1025" width="417" height="243"> </span></p> <p class="BodyText-Contemporary" align="center"><b>Figure #3: Change in Demand by Languages in Last 30 Days</b></p> <h2><a name="SVDifference">The Silicon Valley Difference</a></h2> <p class="BodyText-Contemporary">Silicon Valley still maintains its uniqueness with respect to employment.</p> <p class="BodyText-Contemporary">The percentage of software engineering jobs increased from 25% to 37% of the 180,000+ technical jobs listed. Of these software-engineering openings, 66% are in Silicon Valley. Again, this has not changed from last month and continues to show that Silicon Valley firms use the net by a 2:1 margin over the rest of the country. <h1><a name="WhatsHot">What’s Hot and What’s Not</a></h1> <h2><a name="ProgrammingLinux">Programming Linux</a> </h2> <p class="BodyText-Contemporary">In the last month or so, I have noticed a lot of books on programming the Linux operating system.<span style="mso-spacerun: yes">  </span>Unlike those for programming Windows, all the source code is available and documented. One interesting example is “Open Source Linux Web Programming” by Jones and Batchelor. Done by M&T books. Its ISBN is 0-7645-4619-8. <h1><a name="TechTalk">Tech-Talk</a></h1> <h2><a name="Conversion"></a>Conversion During Initialization<o:p> </o:p> </h2> <p class="MsoNormal">Given two classes, <font face="Courier New" color="#0000FF">A</font> and <font face="Courier New" color="#0000FF">B</font> where there is a conversion constructor from class <font face="Courier New" color="#0000FF">A</font> to class <font face="Courier New" color="#0000FF">B</font>, then:<o:p> </o:p> </p> <blockquote> <p class="MsoNormal"><font face="Courier New" color="#0000FF">A a;<br> B b(a); //explicit convert<o:p> </o:p> </font></p> </blockquote> <p class="MsoNormal">In this case, there’s only one instance of both <font face="Courier New" color="#0000FF">A</font> and <font face="Courier New" color="#0000FF">B</font> with <font face="Courier New" color="#0000FF">b</font> using <font face="Courier New" color="#0000FF">a</font>’s value.</p> <blockquote> <p class="MsoNormal"><font face="Courier New" color="#0000FF">A a;<br> B b=a; //implicit convert<o:p> </o:p> </font></p> </blockquote> <p class="MsoNormal">This format will not work if explicit was specified on the conversion constructor for <font face="Courier New" color="#0000FF">B</font>. Also an implicit conversion is treated as if the copy constructor is called, although it is usually optimized away. An error occurs here if the copy constructor is private.</p> <h2><a name="SmartPointers"></a>Smart pointers in the C++ STL<o:p> </o:p> </h2> <p class="MsoNormal">Again, we are using the book The Standard C++ Library by Nicolai M. Josuttis, Addison Wesley, ISBN 0-201-37926-0 as our source for this column on smart pointers. The smart pointer implementation in the STL is worth discussing because of its semantics.</p> <p class="MsoNormal">First, STL’s <font face="Courier New" color="#0000FF">auto_ptr</font> are used to prevent resource leaks. Using a normal pointer:</p> <blockquote> <p class="MsoNormal"><font face="Courier New" color="#0000FF">struct X{std::string s;};<br> void g(string s);<br> void f(bool b) {<br> X* p=new X;<br> if (b) return;<br> g(p->s);<br> delete px;<br> }<o:p> </o:p> </font></p> </blockquote> <p class="MsoNormal">This badly written example shows a common resource leak: <font face="Courier New" color="#0000FF">px</font> is not freed when the argument, <font face="Courier New" color="#0000FF">b</font>, is false or if <font face="Courier New" color="#0000FF">g()</font> throws an exception. Using the STL’s <font face="Courier New" color="#0000FF">auto_ptr</font> type solves this problem:<span style="font-size:10.0pt"><o:p> </o:p> </span></p> <blockquote> <p class="MsoNormal"><font face="Courier New" color="#0000FF">struct X{std::string s;};<br> void g(string s);<br> void f(bool b) {<br> std::auto_ptr<X>p(new X);<br> if (b) return;<br> g(p->s);<br> }<o:p> </o:p> </font></p> </blockquote> <p>Also, note that there is no delete since all automatic instances of the class <font face="Courier New" color="#0000FF">auto_ptr</font> have their destructor called when the process goes out of scope. In turn, this invokes <font face="Courier New" color="#0000FF">X</font>’s own destructor to free resources allocated to the new instance of <font face="Courier New" color="#0000FF">X</font>. Thus, even this poorly written code works using <font face="Courier New" color="#0000FF">auto_ptr</font>. <o:p> </o:p> </p> <p>STL’s <font face="Courier New" color="#0000FF">auto_ptr</font> implements the idea of ownership: only one instance of an object can be owned by an <font face="Courier New" color="#0000FF">auto_ptr</font> at a time. To accomplish this, certain limitations are imposed – eliminating many possible error sources like pointer arithmetic, <font face="Courier New" color="#0000FF">auto_ptrs</font> arrays, and initializing with ordinary pointers. This latter limitation forces you to initialize <font face="Courier New" color="#0000FF">auto_ptr</font> instances with values, not pointers. Thus: <span style="font-size:10.0pt"><o:p> </o:p> </span></p> <blockquote> <p class="MsoNormal"><font face="Courier New" color="#0000FF">auto_ptr<X> p(new X);// OK<br> auto_ptr<X> q=new X; // err<o:p> </o:p> </font></p> </blockquote> <p>When assigning one <font face="Courier New" color="#0000FF">auto_ptr</font> to an-other, you are really passing ownership from the old to the new <font face="Courier New" color="#0000FF">auto_ptr</font>. Thus, <span style="font-size:10.0pt"><o:p> </o:p> </span></p> <blockquote> <p class="MsoNormal"><font face="Courier New" color="#0000FF">X x1, x2;<br> auto_ptr<X> p1(x1), p2(x2);<br> p1 = p2; // OK<o:p> </o:p> </font></p> </blockquote> <p>First, <font face="Courier New" color="#0000FF">p1</font>’s instance <font face="Courier New" color="#0000FF">x1</font> is freed and then <font face="Courier New" color="#0000FF">p1</font> is set to <font face="Courier New" color="#0000FF">p2</font>’s value. Next, <font face="Courier New" color="#0000FF">p2</font> gets set to null. This implies that the right hand side in <font face="Courier New" color="#0000FF">auto_ptr</font> assignment is changed. No copying is done when transferring ownership. <o:p> </o:p> </p> <p>Nico’s book also discusses transferring ownership to and from functions. It is interesting and fun reading.<span style="font-size:10.0pt"><o:p> </o:p> </span> </td> </tr> </table> <p> </body>