Monday, August 4. 2008Quote of the DaySaturday, July 12. 2008Quote of the DaySunday, July 6. 2008Quote of the DayWednesday, June 4. 2008Single instance per session application with argument passingMonday, June 2. 2008How much would it cost to rewrite it?Monday, May 19. 2008If at first you don't succeed... try, try again...
Here's another interesting piece of code I've just digged up in a C# application I'm reviewing.
If you can come up with a bright idea about what those try/catch blocks are supposed to do, you've got more imagination than me...  class Foo { private int bar; // ...snip... public int GetNewBar() { int ret = 0; lock (this) { try { bar++; ret = bar; } catch { try { bar++; ret = bar; } catch {} } } return ret; } // ...snip... } Wednesday, May 14. 2008Don't code like this at home, kidsFriday, April 18. 2008Quote of the DayThursday, January 24. 2008PHP templates
When you design a complex application, it's always useful to separate the presentation layer from the business logic. Usually, when dealing with web apps, this involves handing templates which are "filled" with data by your controller.
The common rationale is that the template should contain as little logic as possible and that it should be easily editable by non-programmers. There are several PHP packages (Smarty, PHPTal, etc...) that aim at providing a flexible and neat template framework. They usually try to force you not to put code in the template by providing a limited set of directives that can be used, such as placeholders, foreach-style control blocks, conditional blocks... but in the end, every framework I've seen also includes a directive that allows you to put arbitrary PHP code inside the template. Thus I've always wondered: what's the point? Why don't you just use PHP as a templating engine instead of inventing a new language? So, let me introduce my super-duper template class! <?php /* * Copyright ©2007-2008 by Simone Tellini * http://tellini.info/ */ class Template { private static $commonVars = array(); private $tpl; private $vars; public function __construct( $template ) { $this->tpl = $template; $this->vars = self::$commonVars; } // you might set some variables before instantiating your templates when // you want to have some data available in all the templates you need to // build a complex page public static function setCommon( $key, $value ) { self::$commonVars[ $key ] = $value; } public function set( $key, $value ) { $this->vars[ $key ] = $value; } public function execute() { $T = $this->vars; ob_start(); include( $this->tpl ); $html = ob_get_contents(); ob_end_clean(); return( $html ); } } ?> Ta-da! A sample template may look like: <html> <body> Hello, <?= $T[ 'user' ] ?>! </body> </html> The $T array is the only variable visible to the template (except for $this, which points to the Template instance and the super-variables $_GET, $_POST, etc...), since it's the only variable defined in the scope where the template has been include()'d The controller might look like this: <? require_once( 'classes/template.php' ); $tpl = new Template( 'templates/helloWorld.php' ); $tpl->set( 'user', 'World' ); print( $tpl->execute() ); ?> I've been using a class like that for a couple of years now, without any regret. It's been used in sites whose content and graphics are now constantly edited by their owners: even though they aren't programmers, they never had any problem whatsoever in editing or creating their own templates. I truly like it beacuse:
Of course, the fact that you're using PHP to create your templates shouldn't tempt you to start placing business logic inside them! Sunday, January 13. 2008Attributes, reflection and PHP
After a long exposure to .NET, when I get back to PHP I sometimes find myself missing some cool functionality (and a good IDE too... none of those I've tried so far can compete with the comfort of VisualStudio + ReSharper).
Among these missing features, attributes are what I needed in order to solve a certain problem in an elegant way. Looking at what the reflection API was offering, I came up with a simple way to decorate my properties/methods/classes with attributes: through the documentation comments! Let's see an example: <pre> <? class A { /** * @attr * @attr2 */ protected $foo; protected function GetPropAttrs( $property ) { $class = new ReflectionClass( get_class( $this )); $prop = $class->getProperty( $property ); $doc = $prop->getDocComment(); $attrs = array(); $matches = array(); preg_match_all( '/@([a-zA-Z_][a-zA-Z_0-9]*)\s/m', $doc, $matches, PREG_SET_ORDER ); foreach( $matches as $m ) $attrs[] = $m[ 1 ]; return( $attrs ); } public function test() { $attrs = $this->GetPropAttrs( 'foo' ); print_r( $attrs ); } } class B extends A { /** * @attr3 */ protected $foo; } $obj = new A(); print( 'Test A:<br>' ); $obj->test(); $obj = new B(); print( '<p>Test B:<br>' ); $obj->test(); ?> </pre> Running the above script you'll see the following output, confirming that everything works as desired:
If you're using the /** */ comments for real documentation, you might want to use another escape character rather than @, to avoid problems. Happy coding 
Sunday, January 6. 2008Quote of the DayFriday, January 4. 2008Is MySQL bad for (open source) software quality?
I think so.
Why? Because it's basically a toy DBMS with too many non-standard behaviours. A lot of open source projects choose MySQL mainly because it's widely available among hosting providers, while better RDBMS like PostgreSQL1 are hard to find. The real problem is, a lot of open source developer know very little about SQL and databases: they make things up as they proceed in their project, almost often caring only that "it works" for them2. The result is that they learn wrong habits and write poor DB-related code, a trait common to many projects, sadly. For instance, the inspiration for this rant comes from this bug report for Flyspray, a bug reporting system written in PHP. The report is about a pretty lame error in the SQL query used to fetch the task list, as detailed in the 9th comment. PostgreSQL is not "incredibly annoying regarding GROUP BY" as the Flyspray maintainer believes: PostgreSQL simply does the right thing to do in that case, just like every other serious3 RDBMS on the market. I was recently hired to port Flyspray to Oracle: needless to say that I had to fix this problem as well as several other queries. Other examples of DB abuse include Mantis, another PHP bugtracker. If you had a chance to use it, probably you've seen the statistics at the bottom of the page, something like:
I beg your pardon? 43 queries to display a 10 rows table? and why 13 of them have been performed twice? So, please... kids don't use MySQL at home. I'm not saying that you should never use MySQL (there would be plenty of reasons to avoid it anyway ) or that projects based on it suck (I like mantis, for one). It's simply a bad choice for a beginner wishing to learn how to do things properly, IMHO.1 my favorite open source RDBMS. If it seems like I'm doing some advocacy, well... maybe I am 2 I've got nothing against this attitude when it comes to free software: if you want things to get done as you wish, you should be prepared to do them yourself or pay for them, instead of expecting other people to do the dirty work for free 3 yes, that excludes MySQL  Saturday, December 8. 2007The meaning of const in CWednesday, October 3. 2007A little rant about .NET's ReportViewer |
About me Born in Guastalla the 14th of February, 1978; since I was a child I've always enjoyed disassembling (and re-assembling, often succesfully) everything I could put my hands on. Eventually I ended up disassembling and re-assembling software... it's not exactly the same thing as dismantling toys, but it can be equally funny  Nota per i connazionali: la maggior parte di questo sito è in inglese, in modo da poter essere compreso dalla maggior parte delle persone che passano di qui. FlickrLast Reading 
CategoriesShow tagged entriesQuicksearchCalendar
ArchivesSyndicate This Blog |
|||||||||||||||||||||||||||||||||||||||||||||||||
