NAME

       Paranoid::Debug - Trace message support for paranoid programs

VERSION

       $Id: lib/Paranoid/Debug.pm, 2.05 2017/02/06 01:48:57 acorliss Exp $

SYNOPSIS

         use Paranoid::Debug;

         PDEBUG        = 1;
         PDMAXINDENT   = 40;
         PDPREFIX      = sub { scalar localtime };
         pdebug("starting program", 1);
         foo();

         sub foo {
           pdebug("entering foo()", 2);
           pIn();

           pdebug("someting happened!", 2);

           pOut();
           pdebug("leaving w/rv: $rv", 2):
         }

         pderror("error msg");

DESCRIPTION

       The purpose of this module is to provide a useful framework to produce debugging output.
       With this module you can assign a level of detail to pdebug statements, and they'll only
       be displayed to STDERR when PDEBUG is set to that level or higher.  This allows you to
       have your program produce varying levels of debugging output.

       Using the pIn and pOut functions at the beginning and end of each function will cause
       debugging output to be indented appropriately so you can visually see the level of
       recursion.

       NOTE: All modules within the Paranoid framework use this module.  Their debug levels range
       from 9 and up.  You should use 1 - 8 for your own modules or code.

   EXPORT TARGETS
       Only PDEBUG, pdebug, pIn, and pOut are exported by default.  All other functions and
       constants can be exported with the :all tag set.

SUBROUTINES/METHODS

   PDEBUG
       PDEBUG is an lvalue subroutine which is initially set to 0, but can be set to any positive
       integer.  The higher the number the more pdebug statements are printed.

   PDMAXINDENT
       PDMAXINDENT is an lvalue subroutine which is initially set to 60, but can be set to any
       integer.  This controls the max indentation of the debug messages.  Obviously, it wouldn't
       help to indent a debug message by a hundred columns on an eighty column terminal just
       because your stack depth gets that deep.

   PDPREFIX
       PDPREFIX is also an lvalue subroutine and is set by default to a subroutine that returns
       as a string the standard prefix for debug messages:

         [PID - DLEVEL] Subroutine:

       Assigning another reference to a subroutine or string can override this behavior.

   pderror
         pderror("error msg");

       This function prints the passed message to STDERR.

   pdebug
         pdebug("debug statement", 3);
         pdebug("debug statement: %s %2d %.3f", 3, @values);

       This function is called with one mandatory argument (the string to be printed), and an
       optional integer.  This integer is compared against PDEBUG and the debug statement is
       printed if PDEBUG is equal to it or higher.

       The return value is always the debug statement itself.  This allows for a single statement
       to produce debug output and set variables.  For instance:

         Paranoid::ERROR = pdebug("Something bad happened!", 3);

       As an added benefit you can pass a printf template along with their values and they will
       be handled appropriately.  String values passed as undef will be replaced with the literal
       string "undef".

       One deviation from printf allows you to specify a placeholder which can gobble up any
       number of extra arguments while still performing the "undef" substitution:

           pdebug("I was passed these values: %s", 3, @values);

   pIn
         pIn();

       This function causes all subsequent pdebug messages to be indented by one additional
       space.

   pOut
         pOut();

       This function causes all subsequent pdebug messages to be indented by one less space.

DEPENDENCIES

       Paranoid

BUGS AND LIMITATIONS

       pderror (and by extension, pdebug) will generate errors if STDERR is closed elsewhere in
       the program.

AUTHOR

       Arthur Corliss (corliss@digitalmages.com)

LICENSE AND COPYRIGHT

       This software is licensed under the same terms as Perl, itself.  Please see
       http://dev.perl.org/licenses/ for more information.

       (c) 2005 - 2017, Arthur Corliss (corliss@digitalmages.com)