oracular (3) PDL::Demos.3pm.gz

NAME

       PDL::Demos - PDL demo infrastructure

SYNOPSIS

         # in a demo, if text-orientated
         package PDL::Demos::Blah;
         sub info { ('blah', 'Longer description of demo') }
         sub init { 'use PDL::Graphics::PGPLOT;' }
         my @demo = (
           [comment => "Welcome to the Blah demo"],
           [act => <<'EOF'],
         output "PDL can make n-dimensional sequences:\n";
         output $x = sequence(2,3);
         EOF
         );
         sub demo { @demo }
         sub done { "# return things to previous state\n" }

         # a GUI-orientated one
         package PDL::Demos::GUIBlah;
         use GUIBlah; # so demo won't show up in list if GUIBlah not installed
         sub info { ('blahgui', 'GUIBlah demo') }
         sub demo {[actnw => q|
           # starting up the GUI demo app
           |.__PACKAGE__.q|::run();
         |]}
         sub run { # this is just a convention, but a good one
           # ...
         }

         # iterate a demo of your own module - call it PDL::Demos::(something)
         make && perl -Mblib -S perldl # run "demo" and it will see your demo

         # in a CLI or REPL
         use PDL::Demos;
         sub demo {
           if (!$_[0]) {
             require List::Util;
             my @kw = sort grep $_ ne 'pdl', PDL::Demos->keywords;
             my $maxlen = List::Util::max(map length, @kw);
             print "Use:\n";
             printf "   demo %-${maxlen}s # %s\n", @$_[0,1] for map [PDL::Demos->info($_)], 'pdl', @kw;
             return;
           }
           no strict;
           PDL::Demos->init($_[0]);
           $_->[0]->($_->[1]) for PDL::Demos->demo($_[0]);
           PDL::Demos->done($_[0]);
         }

DESCRIPTION

       Provides utilities to make demos for PDL modules.

       PDL demos should be in the "PDL::Demos::*" namespace so that they can be auto-discovered.

       Please ensure that your demo module is included in a CPAN distribution and add it to the appropriate
       metadata (e.g. "Makefile.PL" and "MANIFEST").

METHODS

   list
       Class method; goes through @INC finding all modules starting with "PDL::Demos::" (with up to two
       "::"-separated words). Cached after first run. Does not distinguish demo modules that did not load.

   keywords
       Returns the list of keywords (first element of "info" return-list) of all found modules that loaded
       successfully and implement an "info" method. Caches results.

   info
       Given a keyword, returns the result of calling "info" on the relevant module plus the module name (three
       elements) or throws exception if unknown keyword.

   init
       Given a keyword, "eval"s the result of calling "init" on the relevant module if it has one, or throws
       exception if unknown keyword.

   demo
       Given a keyword, returns the result of calling "demo" on the relevant module or throws exception if
       unknown keyword.

   done
       Given a keyword, "eval"s the result of calling "done" on the relevant module if it has one, or throws
       exception if unknown keyword.

DEMO MODULE METHODS

       Each demo module must provide these class methods:

       info
           Return a two-element list of strings: a single keyword (probably lower-case), and a short description
           of the demo.  Both will be displayed when a user enters "demo" without giving a name.

       demo
           Returns a list of array-refs of two elements: a function provided by this module, and an argument for
           it.

       init
           Return a string of Perl code which will be evaluated in the package running the demo. Use this e.g.
           for "use" statements that import functions needed in your demo.

FUNCTIONS

       These are all exported.

   comment
       Prints its argument, prompts user to press enter before returning.

   output
       Prints its argument (best for use in "actnw" etc).

   actnw
       The argument must be a string containing valid Perl code.  The string is printed with a separator, then
       evaluated as Perl code in the package running the demo, with "PDL" loaded. Doesn't prompt, so use this
       for e.g. GUI demos that return when the user tells them to.

       Multiline code string should start with a newline.

   act
       As above, but prompts before returning.

ERROR HANDLING

       Check the prerequisites (e.g. optional Perl modules) for your demo in your demo module and not only in
       the code string you pass to the "init" routine.  If the code in your demo module dies, then the demo will
       not be offered in the demo overview.  Fatal errors in the init routine will be printed and mess up the
       output layout.  Also, error messages might be difficult to understand if users just want to run the demo.

       If you want to show the demo in the overview though it can't run in the current situation, then make sure
       that your "demo" method informs the user what is missing, and where they can obtain it.

AUTHOR

       Copyright (C) 1998 Tuomas J. Lukka.  Tweaks by Ed J for PDL 2.077, 2022.