NOTES-Perl.md

TOC
===

 - Notes on Perl
 - Notes on Perl on Windows
 - Notes on Perl modules we use
 - Notes on installing a perl module

 Notes on Perl
 -------------

 For our scripts, we rely quite a bit on Perl, and increasingly on
 some core Perl modules.  These Perl modules are part of the Perl
 source, so if you build Perl on your own, you should be set.

 However, if you install Perl as binary packages, the outcome might
 differ, and you may have to check that you do get the core modules
 installed properly.  We do not claim to know them all, but experience
 has told us the following:

 - on Linux distributions based on Debian, the package `perl` will
   install the core Perl modules as well, so you will be fine.
 - on Linux distributions based on RPMs, you will need to install
   `perl-core` rather than just `perl`.

 You MUST have at least Perl version 5.10.0 installed.  This minimum
 requirement is due to our use of regexp backslash sequence \R among
 other features that didn't exist in core Perl before that version.

 Notes on Perl on Windows
 ------------------------

 There are a number of build targets that can be viewed as "Windows".
 Indeed, there are `VC-*` configs targeting VisualStudio C, as well as
 MinGW and Cygwin. The key recommendation is to use "matching" Perl,
 one that matches build environment. For example, if you will build
 on Cygwin be sure to use the Cygwin package manager to install Perl.
 For MSYS builds use the MSYS provided Perl.
 For VC-* builds we recommend Strawberry Perl, from <http://strawberryperl.com>.
 An alternative is ActiveState Perl, from <http://www.activestate.com/ActivePerl>
 for which you may need to explicitly select the Perl module Win32/Console.pm
 available via <https://platform.activestate.com/ActiveState>.

 Notes on Perl on VMS
 --------------------

 You will need to install Perl separately.  One way to do so is to
 download the source from <http://perl.org/>, unpacking it, reading
 `README-VMS.md` and follow the instructions.  Another way is to download a
 `.PCSI` file from <http://www.vmsperl.com/> and install it using the
 POLYCENTER install tool.

 Notes on Perl modules we use
 ----------------------------

 We make increasing use of Perl modules, and do our best to limit
 ourselves to core Perl modules to keep the requirements down.  There
 are just a few exceptions:

  * `Test::More`

    We require the minimum version to be 0.96, which
    appeared in Perl 5.13.4, because that version was
    the first to have all the features we're using.
    This module is required for testing only!
    If you don't plan on running the tests,
    you don't need to bother with this one.

  * `Text::Template`

    This module is not part of the core Perl modules.
    As a matter of fact, the core Perl modules do not
    include any templating module to date.
    This module is absolutely needed,
    configuration depends on it.

 To avoid unnecessary initial hurdles, we have bundled a copy of the
 following modules in our source.  They will work as fallbacks if
 these modules aren't already installed on the system.

    Text::Template

 Notes on installing a perl module
 ---------------------------------

 There are a number of ways to install a perl module.  In all
 descriptions below, `Text::Template` will serve as an example.

 1. for Linux users, the easiest is to install with the use of your
    favorite package manager.  Usually, all you need to do is search
    for the module name and to install the package that comes up.

    On Debian based Linux distributions, it would go like this:

        $ apt-cache search Text::Template
        ...
        libtext-template-perl - perl module to process text templates
        $ sudo apt-get install libtext-template-perl

    Perl modules in Debian based distributions use package names like
    the name of the module in question, with "lib" prepended and
    "-perl" appended.

 2. Install using CPAN.  This is very easy, but usually requires root
    access:

        $ cpan -i Text::Template

    Note that this runs all the tests that the module to be installed
    comes with.  This is usually a smooth operation, but there are
    platforms where a failure is indicated even though the actual tests
    were successful.  Should that happen, you can force an
    installation regardless (that should be safe since you've already
    seen the tests succeed!):

        $ cpan -f -i Text::Template

    Note: on VMS, you must quote any argument that contains upper case
    characters, so the lines above would be:

        $ cpan -i "Text::Template"

    and:

        $ cpan -f -i "Text::Template"