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AutoLoader(3)		       User Contributed Perl Documentation		    AutoLoader(3)

       PDL::AutoLoader - MatLab style AutoLoader for PDL

	use PDL::AutoLoader;
	$a = func1(...);   # Load file func1.pdl
	$b = func2(...);   # Load file func2.pdl

	$PDL::AutoLoader::Rescan = 1; # Enable re-scanning

       This module implements a MatLab style AutoLoader for PDL. If a unknown function 'func()'
       is called then a file 'func.pdl' is searched for and if found is read in to define
       'func()' which is then executed.

       Files are seached for using the directories in seach path @PDLLIB, which is initialised
       from the shell environment variable "PDLLIB" which is a colon seperated list of directo-

       e.g. in csh

	setenv PDLLIB "/home/kgb/pdllib:/local/pdllib"

       Note this is kept seperate from "PERL5LIB" just in case.

       As an added bonus, you can use a leading '+' on a directory name to search not just that
       directory but the entire directory tree under it (excluding symlinks).  The subdirs are
       determined by explicit search, and searches occur at startup and again each time you
       change the number of elements in @PDLLIB.

       For example,
	 setenv PDLLIB "+~kgb/PDL"

       will search /home/kgb/PDL and all its subdirectories for .pdl files.


       The variable $PDL::AutoLoader::Rescan controls whether files are automatically re-scanned
       for changes at the "perldl" command line.

       If "$PDL::AutoLoader::Rescan == 1" and the file is changed then the new definition is
       reloaded auto-matically before executing the "perldl" command line. Which means in prac-
       tice you can edit files, save changes and have "perldl" see the changes automatically.

       The default is '0' - i.e. to have this feature disabled.

       As this feature is only pertinent to the "perldl" shell it imposes no overhead on PDL
       scripts. Yes Bob you can have your cake and eat it too!

       Note: files are only re-evaled if they are determined to have been changed according to
       their date/time stamp.

       No doubt this interface could be improved upon some more. :-)

       Sample file:

	sub foo { # file 'foo.pdl' - define the 'foo' function
	  my $x=shift;
	  return sqrt($x**2 + $x**3 + 2);
	1; # File returns true (i.e. loaded successfully)

       Copyright(C) 1997 Karl Glazebrook (kgb@aaoepp.aao.gov.au); several extensions by Craig
       DeForest (deforest@boulder.swri.edu) All rights reserved. There is no warranty. You are
       allowed to redistribute this software / documentation under certain conditions. For
       details, see the file COPYING in the PDL distribution. If this file is separated from the
       PDL distribution, the copyright notice should be included in the file.

       No doubt this interface could be improved upon some more. :-)

       Will probably be quite slow if "$PDL::AutoLoader::Rescan == 1" and thousands of functions
       have been autoloaded.

       There could be a race condition in which the file changes while the internal autoloader
       code is being executed but it should be harmless.

       Probably has not been tested enough!

perl v5.8.0				    2002-08-06				    AutoLoader(3)
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