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ASP4x::Linker - In-page persistence of widget-specific variables.

=head1 DEPRECATED

L<ASP4> was marked deprecated, so this module is now also deprecated.

=head1 SYNOPSIS

=head2 Setup

(Within /some-page.asp)

  use ASP4x::Linker;
  
  # Create our linker:
  my $linker = ASP4x::Linker->new();
  -or be more specific-
  my $linker = ASP4x::Linker->new( base_href => "/whatever.html" );
  
  # Add a widget:
  $linker->add_widget(
    name  => "widgetA",
    attrs => [qw( page_size page_number sort_col sort_dir )]
  );
  
  # If the page size is changed, go back to page 1:
  $linker->widget("widgetA")->on_change( page_size => sub {
    my ($s) = @_;
    $s->set( page_number => 1 );
  });
  
  # Add another widget:
  $linker->add_widget(
    name  => "widgetB",
    attrs => [qw( keywords tag start_date stop_date )]
  );
  
  # Chained accessor goodness:
  # New as of v1.001
  my $fancy_uri = $linker->widget('widgetA')->set( %args )->uri;

=head2 Setting Variables

Since the C<$linker> starts out with only the variables found in C<$ENV{REQUEST_URI}>
or in the C<base_href> argument, calling C<< $linker->uri() >> on a new linker object
will return the same uri that you are currently on (eg: C</some-page.asp>

To generate links that contain specific attributes, set the attributes for those
widgets and then call C<< $linker->uri() >> to get the resultant uri to match.

  $linker->widget("widgetA")->set( page_number => 2 );
  $uri = $linker->uri;
  # $uri is now "/some-page.asp?widgetA.page_number=2"

=head1 DESCRIPTION

C<ASP4x::Linker> aims to solve the age-old problem of:

B<How do I change one widget on the page without losing my settings for all the other widgets on the page?>

OK - say you have one data grid on your web page that allows paging and sorting.  You can move forward and backward between
pages, change the sorting - life's great.  B<THEN> your boss says:

  We need to have two of those on the same page.  One for Albums and one for Genres.

Now you have 2 options.

=over 4

B<Option 1>: If a user pages "Albums" to page 4, then pages "Genres" to page 2, you forget that "Albums" was on page 4.

B<Option 2>: Use ASP4x::Linker.  Register 2 "widgets" (albums and genres) and let the linker know that they both have C<page_number>, C<page_size>, C<sort_col> and C<sort_dir> attributes.
When the user makes paging or sorting changes in Albums, the stuff for Genres will persist between requests without any extra effort.

=back

=head1 CONSTRUCTOR

=head2 new( [ base_href => $ENV{REQUEST_URI} ] )

Returns a new C<ASP4x::Linker> object using the supplied C<base_href> value as the "starting point"
for all links that will be generated.

If no C<base_href> is provided, the value of C<$ENV{REQUEST_URI}> will be used instead.

=head1 PUBLIC READ-ONLY PROPERTIES

=head2 base_href

Returns the C<base_href> value in use for the linker object.

=head2 widgets

Returns an array of L<ASP4x::Linker::Widget> objects assigned to the linker.

=head1 PUBLIC METHODS

=head2 add_widget( name => $str, attrs => \@attrNames )

Adds a "widget" to the widgets collection.

=head2 widget( $name )

Returns an individual L<ASP4x::Linker::Widget> object by that name.

Returns undef if no widget by that name is found.

=head2 uri( [$properties] )

Returns the uri for all widgets based on the intersect of:

=over 4

=item * The incoming form data from the original request

=item * Individually-set values for each widget in the collection.

=item * Any properties provided as an argument to C<uri()>.

=back

=head2 hidden_fields( [$properties] )

Returns a string of XHTML hidden input fields (<input type="hidden" name="$name" value="$value" />).

Useful if your persistence logic involves repeated form submissions rather than hyperlinks.

The C<$properties> argument is the same as in the C<uri()> method.

=head2 vars( [$properties] )

Returns a hashref representing the intersect of all widgets' names and attributes.

Supposing you setup your linker like this:

  my $linker = ASP4x::Linker->new();
  
  $linker->add_widget(
    name  => 'albums',
    attrs => [qw( page sort )]
  );
  
  $linker->add_widget(
    name  => 'artists',
    attrs => [qw( page sort )]
  );

After calling C<vars()> you'd get:

  $VAR1 = {
    'albums.page'  => undef,
    'albums.sort'  => undef,
    'artists.page' => undef,
    'artists.sort' => undef,
  };

If you did this:

  $linker->vars({
    albums  => {page => 2},
    artists => {sort => 'desc'}
  });

Then you'd get this instead:

  $VAR1 = {
    'albums.page'  => 2,
    'albums.sort'  => undef,
    'artists.page' => undef,
    'artists.sort' => 'desc',
  };

You could also do this: