You can write your own mini (or micro) debuggers to watch your program run. You might want to do this when the other Perl debuggers are too heavyweight (or even too interactive) for your immediate problem. The Devel::Trace module is a simple debugging tool that lets you watch the flow of control as your program [...]
You can use several different Perl modules to inspect data structures. Many of these modules, however, are really two tools in one. Besides showing a data structure as a string, they also serialize the data as Perl code so you can reconstruct the data structure. That second job often makes things hard for you. If [...]
Perl defines two internal pseudo-signals that you can trap. There’s one for die, which I covered in and eventually told you not to use. There’s also one for warn that’s quite safe to use when you need to intercept warnings. To catch a warning, you set a signal handler for the __WARN__ pseudo-signal. The underscores [...]
Data::Dumper, a module that comes in the Standard Library, is one of the great tools knows to Perlers. You give it a big data structure and it pretty prints it for you. If you are one of those people who still believe that the best debugger in the world is print and need to get [...]
As you work in Perl you store each step in source control. When you finish a little bit of work, you commit your work. Ideally, every commit deals with one thing so you’re only introducing one logical change in each revision. Somewhere along the process, you might discover that something is not working correctly. You [...]
In Item 33: “Watch out for match variables, you found out that the match variable $`, $&, and $` come with a performance hit. With all of the module code that you might use, you might be using those variables even though you didn’t code with them yourself. There’s a module that can tell you [...]
Wouldn’t it be great if you could stop your program right before it died so you could see what’s causing the problem? You could start the Perl debugger and step your way to the problem, or set up some break points, but that’s often too much work. The Carp::REPL module let’s you drop into a [...]
We used B::Deparse in Item 7. Know which values are false and test them accordingly, but we didn’t say much about that module. The B namespace has many modules that do various nasty black magic things with the perl parse tree. We showed the example of the default behavior behind while reading from the diamond [...]
