Computer Science & Perl Programming

Chapter 44. Debugging and Devel::

Randy J. Ray

Tip

Since the initial publication of this article, the Devel::* group of modules has flourished, now numbering well over 60 modules. However, all of the information in this article remains current.

You might have learned about Perl’s -d switch, which launches Perl’s internal symbolic debugger. If not, read the perldebug documentation and get started; it lets you set breakpoints and step through your programs line-by-line. The debugger is one of Perl’s most attractive tools for developers, in part because it’s not so much a debugger as a debugging system into which you can place the debugger of your choice. The debuggers can be found in the Devel:: category of the CPAN. In this article, I’d like to describe some of the modules you can find there (listed in Table 44-1).

Table 44-1. Some of the Devel:: modules

Module	Purpose
Devel::DProf	Reports the time used by the program and its subroutines.
Devel::Peek	Displays Perl values and structures.
Devel::SmallProf	Profiles individual lines.
Devel::TraceFuncs	Provides call sequences of subroutines.
Devel::Symdump	Provides symbolic dumps for variables and symbol tables.
Devel::WeakRef	Creates weak references to objects.
Devel::DumpStack	Displays the current subroutine’s stack in human-readable format.
Devel::DebugInit	Creates initialization files for C/C++ symbolic debuggers.
Devel::Coverage	Coverage analysis of Perl scripts and libraries.
Devel::CoreStack	Generates a stack trace from a core dump using the best available ...