S-SymObj
========

:Author:    Steffen (Daode) Nurpmeso
:Contact:   steffen@sdaoden.eu
:Date:      2010 - 2012, 2016
:Copyright: All rights reserved under the terms of the ISC license.
:Status:    Have fun.

.. _`perl(1)`: http://www.perl.org

SymObj.pm provides an easy way to create and construct symbol-tables
and objects.  With a simple hash one defines the fields an object
should have.  An automatically instantiated constructor can then be
used to create the object, and the generated accessor subs implement
a *feed in and forget* approach when they are about to manage arrays
or hashes, trying to handle all kinds of arguments; this is also true
for the constructor.

If debug was enabled upon creation time a constructor which does a lot
of argument checking and more is used, which is pretty useful in times
when the interface is unstable.  Otherwise a different constructor is
used which implements no checking at all; and if the object in question
is the head of a "clean" object tree, one that is entirely managed by
S-SymObj, then indeed a super-fast super-lean constructor implementation
is used that'll rock your house.

The SymObj module is available on CPAN.  The S-SymObj project is located
at https://www.sdaoden.eu/code.html.  It is developed using a git(1)
repository, which is located at git://git.sdaoden.eu/s-symobj.git.
A SourceForge.net mirror is at git.code.sf.net/p/ssymobj/code (or browse it
at http://sourceforge.net/p/ssymobj/code/), and a GitLab.com mirror is at
https://gitlab.com/sdaoden/s-symobj.git (browse it at
https://gitlab.com/sdaoden/s-symobj/).

Installation
------------

Since v0.6.0 [S-]SymObj is available on CPAN as SymObj.  Please see
the standard ``$ man 1 cpan`` (and maybe ``$ man 1 perlmodinstall``)
manual(s) for how to perform a regular installation from CPAN.
In short: ``$ cpan SymObj``.

But In general SymObj.pm is a Perl module and therefore needs to be
in ``@INC`` if scripts should be able to find it easily.  This can be
accomplished by placing the SymObj.pm somewhere and either specifying
the path via the ``-I`` command line option, or, and that is maybe the
easiest and most flexible solution, by placing it in the ``PERL5LIB``
environment variable.  Here is how to do that in a Bourne/Korn/POSIX
shell: ::

   $ PERL5LIB=/PATH/TO/SymObj.pm PERL5OPT=-C
   $ export PERL5LIB PERL5OPT

Usage
-----

The complete and up-to-date documentation is part of the S-SymObj
module itself -- if that has been regularly installed via CPAN as shown
above, then the manual should show up by typing ``$ man SymObj``,
otherwise the ``pod2XY`` family of programs can be used directly upon
SymObj.pm, as in ``$ pod2text SymObj.pm``.  The POD example as of
2012-09-12: ::

   use diagnostics -verbose;
   use strict;
   use warnings;
   # You need to require it in a BEGIN{}..; try out $Debug= 1/2
   BEGIN { require SymObj; $SymObj::Debug = 0; }

   # Accessor subs return references for hashes and arrays (but shallow
   # copy in wantarray context) scalars are returned "as-is"
   {package X1;
      SymObj::sym_create(SymObj::NONE, { # (NONE is 0..)
         _name => '', _array => [qw(Is Easy)],
         _hash => {To => 'hv1', Use => 'hv2'} });
   }
   my $o = X1->new(name => 'SymObj');
   print $o->name, ' ';
   print join(' ', @{$o->array}), ' ';
   print join(' ', keys %{$o->hash}), "\n";

   # Unknown arguments are detected when DEBUG/VERBOSE is enabled.
   {package X2;
      our @ISA = ('X1');
      SymObj::sym_create(0, {}); # <- adds no fields on its own
   }
   # (Clean hierarchy has optimized constructor which is used, then)
   if ($SymObj::Debug != 0) {
      $o = X2->new(name => 'It detects some misuses (if $Debug > 0)',
         'un' => 'known argument catched');
   } else {
      $o = X2->new(name => 'It detects some misuses (if $Debug > 0)');
   }
   print $o->name, "\n";

   # Fields which mirror fieldnames of superclasses define overrides.
   {package X3;
      our @ISA = ('X2');
      SymObj::sym_create(0, { '_name' => 'Auto superclass-ovw'},
         sub { my $self = shift; print "X3 usr ctor\n"; });
   }
   $o = X3->new();
   print $o->name, "\n";

   # One may enforce creation of array/hash accessors even for undef
   # values by using the @/% type modifiers; the objects themselves
   # are lazy-created as necessary, then...
   {package X4;
      our @ISA = ('X3');
      SymObj::sym_create(0, { '%_hash2'=>undef, '@_array2'=>undef });
      sub __ctor { my $self = shift; print "X4 usr ctor\n"; }
   }
   $o = X4->new(name => 'A X4');
   die 'Lazy-allocation failed'
      if ! defined $o->hash2 || ! defined $o->array2;
   print join(' ', keys %{$o->hash2(Allocation=>1, Lazy=>1)}), ' ';
   print join(' ', @{$o->array2(qw(Can Be Used))}), "\n";

   %{$o->hash2} = ();
   $o->hash2(HashAndArray => 'easy');
   $o->hash2(qw(Accessors development));
   $o->hash2('Really', 'is');
   $o->hash2(['Swallow', 'possible']);
   $o->hash2({ Anything => 'here' });
   print join(' ', keys %{$o->hash2}), "\n";
   # P.S.: this is also true for the constructor(s)

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