Provided by: libparanoid-perl_2.09-1_all 
NAME
Paranoid::Debug - Trace message support for paranoid programs
VERSION
$Id: lib/Paranoid/Debug.pm, 2.09 2021/12/28 15:46:49 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.
IMPORT LISTS
This module exports the following symbols by default:
PDEBUG pdebug pIn pOut
The following specialized import lists also exist:
List Members
--------------------------------------------------------
constants PDEBUG1 PDEBUG2 PDEBUG3 PDEBUG4 PDEBUG5
PDEBUG6 PDEBUG7 PDEBUG8
all @defaults @constants
pderror PDPREFIX PDLEVEL1 PDLEVEL2
PDLEVEL3 PDLEVEL4 PDMAXINDENT
CONSTANTS
PDEBUG1 - PDEBUG8
There are eight constants exported by default for use by developers that allow for up to
eight levels of diagnostic output. None of these levels are used by internal Paranoid
code, they are reserved for use by third parties.
PDLEVEL1 - PDLEVEL4
These constants are not intended for use by other modules, rather the exist for the
internal debug levels used by all Paranoid::* modules.
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.
PDPREFIX
PDPREFIX is an lvalue subroutine that contants a code reference to a subroutine that
returns an appropriate prefix for debug messages. The default subroutine prints an
indented string (indented according to depth on the call stack) that prints the process
PID, debug level, and the current routine/or method that pdebug was called in.
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 code reference 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. The
only argument that will be passed to any such routine will be the name of the calling
subroutine.
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 free software. Similar to Perl, you can redistribute it and/or modify it
under the terms of either:
a) the GNU General Public License
<https://www.gnu.org/licenses/gpl-1.0.html> as published by the
Free Software Foundation <http://www.fsf.org/>; either version 1
<https://www.gnu.org/licenses/gpl-1.0.html>, or any later version
<https://www.gnu.org/licenses/license-list.html#GNUGPL>, or
b) the Artistic License 2.0
<https://opensource.org/licenses/Artistic-2.0>,
subject to the following additional term: No trademark rights to "Paranoid" have been or
are conveyed under any of the above licenses. However, "Paranoid" may be used fairly to
describe this unmodified software, in good faith, but not as a trademark.
(c) 2005 - 2020, Arthur Corliss (corliss@digitalmages.com) (tm) 2008 - 2020, Paranoid Inc.
(www.paranoid.com)