MusicRoom::Context - Bind variables to values for MusicRoom processes

MusicRoom documentation Contained in the MusicRoom distribution.

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NAME

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MusicRoom::Context - Bind variables to values for MusicRoom processes

DESCRIPTION

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This package tracks the values that variables have for MusicRoom processes. The key action here is to maintain values so that running processes can keep track, to serialise them into the database so we can store them between runs and to extract them from the database.

MusicRoom documentation Contained in the MusicRoom distribution. 
package MusicRoom::Context;


use strict;
use warnings;
use Carp;

sub new
  {
    my $class = shift;
    my $self = bless 
      {
        # UNIX time of last save/restore
        timestamp => -1,
        parent => undef,
        vars => {},
      },$class;

    $self->{needs_saving} = 0;

    return $self;
  }

sub get
  {
    my($self,$name) = @_;

    return $self->{vars}->{$name}
                 if(defined $self->{vars}->{$name});

    my $val;

    $val = $self->{parent}->get($name)
                 if(defined $self->{parent});
    if(!defined $val)
      {
        carp("Undefined var $name in context $self->{id}");
        return undef;
      }
    return $val;
  }

sub set
  {
    my($self,$name,$val) = @_;
    
    if(!defined $self->{vars}->{$name})
      {
        # Do we complain about setting an as yet undefined value?
        $self->{vars}->{$name} = "";
      }
    $self->{vars}->{$name} = $val;
    $self->{needs_saving} = 1;
  }

sub DESTROY
  {
    my($self) = @_;

    if($self->{needs_saving})
      {
        carp("Destroying modified context");
      }
  }

sub save
  {
    my($self) = @_;

    # Write the current value of the context into the database

    # Note that the current settings have been saved
    $self->{needs_saving} = 0;
  }

sub restore
  {
    my($self) = @_;

    # Note that the current settings have been saved
    $self->{needs_saving} = 0;
  }

1;