Perl
Some people always complain, even about the language they've been working with for years while they has other options. One of them recently complained that Perl cleans up objects in unpredictable order during global destruction (after exit; and all END blocks). Here is what happend, how we tracked it down and solved it.
Data is getting bigger and bigger as technology advances. We didn't even think about using something inefficent like XML when I started writing sourcecode on a Datapoint 6600 or even in MS-DOS world, but today? A meg more or less doesn't matter today. But sometimes space is still premium and so it is for my current project. I'm working with short strings (text plus some extra chars, about 6 bit per char) and they should be compressed.
SQL has some drawbacks, the worst one might be the SQL injection chance. There are many ways to avoid them but few of them are really working, one of them is using bind values by replacing all values by ? and passing the real values at execution time.
mySQL servers have their own mind and sometimes just disappear. They go away from a client leaving it alone if the complete server is dying, if a client is doing unexpected things and sometimes even without any known reason.
Race conditions are nice: Two (or more) tasks are fighting for the same thing at the same time. Row locking on the database may help to avoid such races but only if the database supports them.
The Perl CGI module is commonly used, but it's heavy. CGI::Simple is more lightweight but lacks some features. Here is a feature not supported by CGI but by CGI::Simple.
I recently announced an article about Gearman, today I'ld like to start with setting up a Gearman dispatcher server.
Web scripts usually do one thing at a time which is quite good as long as there is not too much to do. But serving thousands of request per minute with thousands of source code lines per request starts getting challenging. Bon Jovi asked for help for web scripts some time ago by writing his song "(Whos gonna) work for the working man". Well, there are little chances that he had something else in mind, but who cares.
Typical Perl scripts (and others running as CGI-scripts) run and exit once they're done, but this isn't very efficient with medium or high request counts. Persistent solutions like FCGI and ModPerl avoid the additional interpreter loading and compiling phases, but start being challenging if any source file is changed.
Doing many checks may slow down a program, but sorting the tests may improve your program's speed a lot at a very low cost.
Actually not a 100% real one, but something near by, like this one (near the end of the text).
Crossword puzzle creators must know and remember many words, but everybody could create one with a little help by a computer.
SQL injections are well-known and could easily be used against against most PHP scripts, but there is a much easier injection leak in many Perl scripts: Regular Expression injection.
A blog comment resulting in a new post? Yes, a guy from southern Germany made me do this by trying to use the whole alphabet in his comment.
DBI is the universal Perl database interface but it's using a so-called DBD driver module for each database type. I've been searching but didn't find a DBD module fitting my needs and so I started writing a new one.
IO::CaptureOutput is a great module but provides limited control. Here is a quick hack to replace the capture_exec function while getting more control about what is being done.
