Chapter 4

Debugging

Perl comes with a command line debugger similar to the popular gdb C debugger. 

If you've never used the Perl debugger before, you should look at the perldebug

documentation to get started. To run the Perl debugger on a single test.pl test 

script, use the command make testdb:

$ make testdb

PERL_DL_NONLAZY=1 /usr/local/bin/perl  d  Iblib/arch  Iblib/lib \

 I/usr/local/lib/perl5/5.6.1/i686 linux  I/usr/local/lib/perl5/5.6.1 test.pl

Default die handler restored.

Loading DB routines from perl5db.pl version 1.07

Editor support available.

Enter h or  h h  for help, or  man perldebug  for more help.

1..1

main::(test.pl:4):      ok(1); # If we made it this far, we re ok.

  DB<1>

However, if you're using a t directory of test scripts, then a simple make testdb won't 

work. This is because the debugger will only work on a single script. To use the 

debugger on a single .t file, include the option TEST_FILE. For example, to run 

t/02basic.t under the debugger, you would use the following command:

make testdb TEST_FILE=t/02basic.t

Multimodule Distributions

A module distribution can contain more than one module file. A common use for 

packaging multiple files in a distribution is to install a family of modules in a 

common namespace. For example, the HTML::Template::JIT

15

 module distribution 

contains the three modules HTML::Template::JIT, HTML::Template::JIT::Compiler, 

and HTML::Template::JIT::Base. The main module file, JIT.pm, is placed where you 

would expect it in the module distribution directory. The other two, Compiler.pm

and Base.pm, are placed in a directory called JIT. Makefile.PL automatically finds 

the two submodules and installs them along with JIT.pm.

15. HTML::Template::JIT provides a just in time compiler for HTML::Template. The module was 

written by myself, Sam Tregar, and is available on CPAN.

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