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This article mainly introduces how to debug Perl in Perl language. It is very detailed and has certain reference value. Friends who are interested must finish reading it.

Skills of Perl debugging

The trouble caused by mistakes

Software developers often underestimate the importance of software testing. The root cause of this phenomenon is simple: it is difficult to deal with errors! Because errors often expose fundamental flaws in the code, developers sometimes even rewrite major parts of the project from scratch for a few errors.

I think debugging is so important that at least 30% of the time of the entire project should be allocated to it. The extra debugging time will lead to a better product. On the other hand, if you shorten debugging time in order to release the software faster, you will spend double time fixing problems that are exposed later after the software is generated.

There are three basic types of errors: coding errors, documentation errors, and requirements errors. Requirements errors are usually caused by loose requirements or lack of requirements. Documentation errors exist in manuals or online help. Coding errors are caused by programmers' errors in implementing requirements. Unfortunately, requirements and documentation errors are beyond the scope of this article, so we only discuss how to "detect", "resolve", and "fix" coding errors.

Basic concepts of Perl debugging

We have defined coding errors as errors that programmers make when implementing requirements. Coding errors can lead to incorrect program behavior (behavior that deviates from requirements). Therefore, the first thing a programmer should know before writing or debugging a program is the program requirements.

Perl debugging is no different from hunting. The step is to detect the error (by observing the behavior of the error and confirming its pattern). At this stage, mistakes are just symptoms.

The second step is to solve the mistake. Because errors must be eliminated in the source code, someone who is proficient in the program should check for errors and know the root cause of these errors. If the code is easier to understand, and there is no more code now than in the wrong version, you may be right.

The third step, which is also a * step, is to fix the error (note that there is a difference between "fix" and "fix"). The debugger puts the source code changes into the "live" production process and then checks to see if it is correct. If the code is incorrect, you have not resolved the error, or even worse, a new error may have been introduced. Since the purpose of resolving errors should not be to introduce new errors, be sure to fix each error after you resolve it.

To ensure that errors are quickly found and well understood, you should be well aware of how your program uses modules and classes at each major branch during debugging. Of course, this requires an in-depth understanding of the language in which the code is written (in our example, Perl). Because of all these requirements, it is difficult to find good software testers.

Perl Debugger

The resources of Perl programmers are debuggers that come with Perl. As you can see, it is very easy to get started with this debugger.

Run a script with the debugger

Perl-dprogram.pl

The Perl debugger comes with help ('h' or 'hh' is used for detailed and short help screens, respectively). The perldocperldebug page (enter "perldocperldebug" in the command prompt window) has a more complete description of the Perl debugger.

Conclusions about the Perl Debugger

The Emacs editor supports the Perl debugger and makes it easier to use. You can use Info (enter M-xinfo) in Emacs to read more details about GUDEmacs. GUD is a global debugging method that works with the Perl debugger (enter M-xperldb when editing Perl programs in Emacs).

With a little effort, the vi series of editors can also support the Perl debugger. For more information, see the perldocperldebug page. For information about other editors, refer to the documentation for each editor.

Perl's built-in debugger is a powerful tool for performing tasks that are much more complex than the simple usage we just saw. But it does require users to have a lot of Perl expertise. Because of this, we will now look at some simpler tools that will be more suitable for beginner and intermediate Perl programmers.

Devel::ptkdb

To use the Devel::ptkdb debugger, first download it from CPAN (see Resources below) and install it on your system. (some users may also need to install the Tk module, which is also available from CPAN. In my opinion, Devel::ptkdb is used on UNIX systems (such as Linux). Although in theory Devel::ptkdb is not limited to UNIX-compatible systems, I have never heard of anyone successfully using Devel::ptkdb on Windows. As an old saying goes: anything is possible except skiing through the revolving door. )

If you cannot get your system administrator to install it for you (for example, because you are a system administrator yourself), you can try the following at the command prompt (you may need to do this as root):

Install Devel::ptkdb from CPAN

Perl-MCPAN-e'installTk'

Perl-MCPAN-e'installDevel::ptkdb'

If the CPAN installation routine is run * * times, the appropriate module will be downloaded and installed automatically after answering some initial questions.

You can run the program using the ptkdb debugger, as follows (using our previous buggy.pl example):

Use Devel::ptkdb

Perl-d:ptkdbbuggy.plbuggy.pl

To read the documentation for the Devel::ptkdb module, use the command "perldocDevel::ptkdb". We use version 1.1071 in this article.

The above is all the contents of the article "how to debug Perl in Perl language". Thank you for reading! Hope to share the content to help you, more related knowledge, welcome to follow the industry information channel!

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