AutoLoader(3) User Contributed Perl Documentation AutoLoader(3)NAMEPDL::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 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.
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 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 + $x**3 + 2);
}
1; # File returns true (i.e. loaded successfully)
AUTHORCopyright(C) 1997 Karl Glazebrook (kgb@aaoepp.aao.gov.au); several
extensions by Craig DeForest (deforest@boulder.swri.edu) All rights
reserved. There is no warranty. You are allowed to redistribute this
software / documentation under certain conditions. For details, see the
file COPYING in the PDL distribution. If this file is separated from
the PDL distribution, the copyright notice should be included in the
file.
BUGS
No doubt this interface could be improved upon some more. :-)
Will probably be quite slow if "$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!
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.
perl v5.10.0 2003-10-08 AutoLoader(3)
