AutoLoader(r)  User Contributed Perl Documentation  AutoLoader(r)



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 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
       directories.

       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 direc-
       tory 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 ele-
       ments in @PDLLIB.

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

       will search /home/kgb/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" 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)


AUTHOR
       Copyright(t) 1997 Karl Glazebrook (kgb@aaoepp.aao.gov.au).
       All rights reserved. There is no warranty. You are allowed
       to redistribute this software / documentation under cer-
       tain 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!



perl v5.6.1                 2001-09-29              AutoLoader(r)