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A debugger is a computer program that is used to debug other programs. Devel::ebug is a simple, extensible Perl debugger with a clean API. Using this module, you may easily write a Perl debugger to debug your programs. Alternatively, it comes with an interactive debugger, ebug. perl5db.pl, Perl's current debugger is currently 2,600 lines of magic and special cases. The code is nearly unreadable: fixing bugs and adding new features is fraught with difficulties. The debugger has no test suite which has caused breakage with changes that couldn't be properly tested. It will also not debug regexes. Devel::ebug is aimed at fixing these problems and delivering a replacement debugger which provides a well-tested simple programmatic interface to debugging programs. This makes it easier to build debuggers on top of Devel::ebug, be they console-, curses-, GUI- or Ajax-based. There are currently two user interfaces to Devel::debug, ebug and ebug_http. ebug is a console-based interface to debugging programs, much like perl5db.pl. ebug_http is an innovative web-based interface to debugging programs.

The callsite() function returns the callsite (a number) one level up from where it was called. See the tests for an example. It's useful for functions that need to uniquely know where they were called, such as Every::every() (see devel/p5-Every).

Devel::Diagram scans the given Perl modules attempting to discover the class structure. It produces a hash table that can be converted to XML (or other formats) via Render(). An XSL stylesheet is included that converts the XML class diagram into HTML.

The Devel::SmallProf profiler is focused on the time taken for a program run on a line-by-line basis. It is intended to be as "small" in terms of impact on the speed and memory usage of the profiled program as possible and also in terms of being simple to use.

Devel::PartialDump is a data dumper optimized for logging of arbitrary parameters. It attempts to truncate overly verbose data, in a way that is hopefully more useful for diagnostics warnings than warn Dumper(@stuff); Unlike other data dumping modules there are no attempts at correctness or cross referencing, this is only meant to provide a slightly deeper look into the data in question.

The Devel::Profile package is a Perl code profiler. This will collect information on the execution time of a Perl script and of the subs in that script. This information can be used to determine which subroutines are using the most time and which subroutines are being called most often.

This module lets you add debugging instructions which look like comments and do nothing unless you 'use' this module. use Devel::StealthDebug; my $foo = 0; # ... Several processing on $foo my $bar = 1 / $foo; #!assert($foo != 0)! my %myhash; #!watch(%myhash)! sub func1 { #!emit(Entering func1)! #... }

The Devel::Required module only serves a purpose in the development environment of an author of a CPAN module (or more precisely: a user of the ExtUtils::MakeMaker module). It makes sure that any changes to the required modules specified in the Makefile.PL are automatically reflected in the appropriate text file and in the appropriate source files (either explicitly or implicitly specified). It takes the information given with the PREREQ_PM parameter and by default writes this to the README file, as well as to the POD of the file specified with the VERSION_FROM parameter. Both these defaults can be overridden with the "text" and "pod" parameters in the use Devel::Required specification.

Declaring constants is very convenient for writing programs, but as they're often inlined by Perl, retrieving their symbolic names can be tricky. This is made worse with low level modules that use constants for bit-twiddling. Devel::Constants makes this much more manageable. It silently wraps around the constant module, intercepting all constant declarations. It builds a hash, associating the values to their names. The names can then be retrieved as necessary.

Devel::Leak has two functions NoteSV and CheckSV. NoteSV walks the perl internal table of allocated SVs (scalar values) - (which actually contains arrays and hashes too), and records their addresses in a table. It returns a count of these "things", and stores a pointer to the table (which is obtained from the heap using malloc()) in its argument. CheckSV is passed argument which holds a pointer to a table created by NoteSV. It re-walks the perl-internals and calls sv_dump() for any "things" which did not exist when NoteSV was called. It returns a count of the number of "things" now allocated.