NAME

       PDL::AutoLoader - MatLab style AutoLoader for PDL

SYNOPSIS

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

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

DESCRIPTION

       This module implements a MatLab style AutoLoader for PDL. If an unknown function "func()"
       is called, PDL looks for a file called "func.pdl".  If it finds one, it compiles the file
       and calls the function "func".

       The list of directories to search in is given by the shell environment variable "PDLLIB".
       This is a colon-separated list of directories. On MSWindows systems, is it a semicolon
       -separated list of directories.

       For example, in csh:

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

       Note: This variable is unrelated to Perl's "PERL5LIB".

       If you add a leading '+' on a directory name, PDL will search the entire directory tree
       below that point. Internally, PDL stores the dirctory list in the variable @PDLLIB, which
       can be modified at run time.

       For example, in csh:

         setenv PDLLIB "+/home/joe/PDL"

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

   AUTO-SCANNING
       The variable $PDL::AutoLoader::Rescan controls whether files are automatically re-scanned
       for changes at the "perldl" or "pdl2" command line.

       If "$PDL::AutoLoader::Rescan == 1" and the file is changed then the new definition is
       reloaded auto-matically before executing the "perldl" or "pdl2" command line. Which means
       in practice you can edit files, save changes and have "perldl" or "pdl2" see the changes
       automatically.

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

       As this feature is only pertinent to the PDL 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)

AUTHOR

       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.

BUGS

       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!

SEE ALSO

       For an alternative approach to managing a personal collaction of modules and functions,
       see local::lib.

   PDL::AutoLoader::expand_path
       Expand a compactified path into a dir list

       You supply a pathlist and leading '+' and '~' characters get expanded into full
       directories.  Normally you don't want to use this -- it's internal to the autoloader --
       but some utilities, like the online documentation searcher, need to be able to use it.