Alien::Gnuplot(3pm)

NAME
Alien::Gnuplot - Find and verify functionality of the gnuplot executable.

SYNOPSIS
 package MyGnuplotter;

 use strict;

 use Alien::Gnuplot;

 $gnuplot = $Alien::Gnuplot::executable;

 `$gnuplot < /tmp/plotfile`;

 1;

DESCRIPTION
Alien::Gnuplot verifies existence and sanity of the gnuplot external application. It only declares one access method, "Alien::Gnuplot::load_gnuplot", which does the actual work and is called automatically at load time. Alien::Gnuplot doesn't have any actual plotting methods - making use of gnuplot, once it is found and verified, is up to you or your client module.

Using Alien::Gnuplot checks for existence of the executable, verifies that it runs properly, and sets several global variables to describe the properties of the gnuplot it found:

•   $Alien::Gnuplot::executable

    gets the path to the gnuplot executable.

•   $Alien::Gnuplot::version

    gets the self-reported version number of the executable.

•   $Alien::Gnuplot::pl

    gets the self-reported patch level.

•   @Alien::Gnuplot::terms

    gets a list of the names of all supported terminal devices.

•   %Alien::Gnuplot::terms

    gets a key for each supported terminal device; values are the 1-line description from gnuplot. This is useful for testing whether a particular terminal is supported.

•   @Alien::Gnuplot::colors

    gets a list of the names of all named colors recognized by this gnuplot.

•   %Alien::Gnuplot::colors

    gets a key for each named color; values are the "#RRGGBB" form of the color. This is useful for decoding colors, or for checking whether a particular color name is recognized. All the color names are lowercase alphanumeric.

You can point Alien::Gnuplot to a particular path for gnuplot, by setting the environment variable GNUPLOT_BINARY to the path. Otherwise your path will be searched (using File::Spec) for the executable file.

If there is no executable application in your path or in the location pointed to by GNUPLOT_BINARY, then the module throws an exception. You can also verify that it has not completed successfully, by examining $Alien::Gnuplot::version, which is undefined in case of failure and contains the gnuplot version string on success.

If you think the global state of the gnuplot executable may have changed, you can either reload the module or explicitly call Alien::Gnuplot::load_gnuplot() to force a fresh inspection of the executable.

INSTALLATION STRATEGY
When you install Alien::Gnuplot, it checks that gnuplot itself is installed as well. If it is not, then Alien::Gnuplot attempts to use one of several common package managers to install gnuplot for you. If it can't find one of those, if dies (and refuses to install), printing a friendly message about how to get gnuplot before throwing an error.

In principle, gnuplot could be automagically downloaded and built, but it is distributed via Sourceforge -- which obfuscates interior links, making such tools surprisingly difficult to write.

CROSS-PLATFORM BEHAVIOR
On POSIX systems, including Linux and MacOS, Alien::Gnuplot uses fork/exec to invoke the gnuplot executable and asynchronously monitor it for hangs. Microsoft Windows process control is more difficult, so if $^O contains "MSWin32", a simpler system call is used, that is riskier -- it involves waiting for the unknown executable to complete.

REPOSITORIES
Gnuplot's main home page is at <https://gnuplot.sourceforge.net/>.

Alien::Gnuplot development is at <https://github.com/drzowie/Alien-Gnuplot>.

A major client module for Alien::Gnuplot is PDL::Graphics::Gnuplot, which can be found at <https://github.com/PDLPorters/PDL-Graphics-Gnuplot>. PDL is at <https://pdl.perl.org/>.

AUTHOR
Craig DeForest <craig@deforest.org>

(with special thanks to Chris Marshall, Juergen Mueck, and Sisyphus for testing and debugging on the Microsoft platform)

COPYRIGHT AND LICENSE
Copyright (C) 2013 Craig DeForest

This library is free software; you can redistribute it and/or modify it under the same terms as Perl itself.