Christian Soeller > PDL-2.4.3 > PDL::AutoLoader


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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 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 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 practice 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 (; several extensions by Craig DeForest ( 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.



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!


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.

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