Padre::DB::LastPositionInFile - Storage class for stateful cursor positions

  Padre::DB::LastPositionInFile->set_last_pos($file, $pos);
  my $pos = Padre::DB::LastPositionInFile->get_last_pos($file);

This class allows storing in Padre's database the last cursor position in a file. This is useful in order to put the cursor back to where it was when re-opening this file later on.

Please note that due to limitations in the way we generate the class, imposed by ORLite, automatic translation for Portable Perl is only applied if you use the set_last_pos and get_last_pos methods.

  set_last_pos( $file, $pos )

Record $pos as the last known cursor position in $file.

Applies appropriate path translation if we are running in Portable Perl.

  get_last_pos( $file )

Return the last known cursor position for $file. Return undef if no position was recorded for this file.

Applies appropriate path translation if we are running in Portable Perl.

  # Returns 'Padre::DB'
  my $namespace = Padre::DB::LastPositionInFile->base;

Normally you will only need to work directly with a table class, and only with one ORLite package.

However, if for some reason you need to work with multiple ORLite packages at the same time without hardcoding the root namespace all the time, you can determine the root namespace from an object or table class with the base method.

  # Returns 'last_position_in_file'
  print Padre::DB::LastPositionInFile->table;

While you should not need the name of table for any simple operations, from time to time you may need it programatically. If you do need it, you can use the table method to get the table name.

  my $object = Padre::DB::LastPositionInFile->load( $name );

If your table has single column primary key, a load method will be generated in the class. If there is no primary key, the method is not created.

The load method provides a shortcut mechanism for fetching a single object based on the value of the primary key. However it should only be used for cases where your code trusts the record to already exists.

It returns a Padre::DB::LastPositionInFile object, or throws an exception if the object does not exist.

  # Get all objects in list context
  my @list = Padre::DB::LastPositionInFile->select;

  # Get a subset of objects in scalar context
  my $array_ref = Padre::DB::LastPositionInFile->select(
      'where name > ? order by name',
      1000,
  );

The select method executes a typical SQL SELECT query on the last_position_in_file table.

It takes an optional argument of a SQL phrase to be added after the FROM last_position_in_file section of the query, followed by variables to be bound to the placeholders in the SQL phrase. Any SQL that is compatible with SQLite can be used in the parameter.

Returns a list of Padre::DB::LastPositionInFile objects when called in list context, or a reference to an ARRAY of Padre::DB::LastPositionInFile objects when called in scalar context.

Throws an exception on error, typically directly from the DBI layer.

  Padre::DB::LastPositionInFile->iterate( sub {
      print $_->name . "\n";
  } );

The iterate method enables the processing of large tables one record at a time without loading having to them all into memory in advance.

This plays well to the strength of SQLite, allowing it to do the work of loading arbitrarily large stream of records from disk while retaining the full power of Perl when processing the records.

The last argument to iterate must be a subroutine reference that will be called for each element in the list, with the object provided in the topic variable $_.

This makes the iterate code fragment above functionally equivalent to the following, except with an O(1) memory cost instead of O(n).

  foreach ( Padre::DB::LastPositionInFile->select ) {
      print $_->name . "\n";
  }

You can filter the list via SQL in the same way you can with select.

  Padre::DB::LastPositionInFile->iterate(
      'order by ?', 'name',
      sub {
          print $_->name . "\n";
      }
  );

You can also use it in raw form from the root namespace for better control. Using this form also allows for the use of arbitrarily complex queries, including joins. Instead of being objects, rows are provided as ARRAY references when used in this form.

  Padre::DB->iterate(
      'select name from last_position_in_file order by name',
      sub {
          print $_->[0] . "\n";
      }
  );

  # How many objects are in the table
  my $rows = Padre::DB::LastPositionInFile->count;

  # How many objects 
  my $small = Padre::DB::LastPositionInFile->count(
      'where name > ?',
      1000,
  );

The count method executes a SELECT COUNT(*) query on the last_position_in_file table.

It takes an optional argument of a SQL phrase to be added after the FROM last_position_in_file section of the query, followed by variables to be bound to the placeholders in the SQL phrase. Any SQL that is compatible with SQLite can be used in the parameter.

Returns the number of objects that match the condition.

Throws an exception on error, typically directly from the DBI layer.

  TO BE COMPLETED

The new constructor is used to create a new abstract object that is not (yet) written to the database.

Returns a new Padre::DB::LastPositionInFile object.

  my $object = Padre::DB::LastPositionInFile->create(

      name => 'value',

      position => 'value',

  );

The create constructor is a one-step combination of new and insert that takes the column parameters, creates a new Padre::DB::LastPositionInFile object, inserts the appropriate row into the last_position_in_file table, and then returns the object.

If the primary key column name is not provided to the constructor (or it is false) the object returned will have name set to the new unique identifier.

Returns a new last_position_in_file object, or throws an exception on error, typically from the DBI layer.

  $object->insert;

The insert method commits a new object (created with the new method) into the database.

If a the primary key column name is not provided to the constructor (or it is false) the object returned will have name set to the new unique identifier.

Returns the object itself as a convenience, or throws an exception on error, typically from the DBI layer.

  # Delete a single instantiated object
  $object->delete;

  # Delete multiple rows from the last_position_in_file table
  Padre::DB::LastPositionInFile->delete('where name > ?', 1000);

The delete method can be used in a class form and an instance form.

When used on an existing Padre::DB::LastPositionInFile instance, the delete method removes that specific instance from the last_position_in_file, leaving the object intact for you to deal with post-delete actions as you wish.

When used as a class method, it takes a compulsory argument of a SQL phrase to be added after the DELETE FROM last_position_in_file section of the query, followed by variables to be bound to the placeholders in the SQL phrase. Any SQL that is compatible with SQLite can be used in the parameter.

Returns true on success or throws an exception on error, or if you attempt to call delete without a SQL condition phrase.

  # Delete all records in the last_position_in_file table
  Padre::DB::LastPositionInFile->truncate;

To prevent the common and extremely dangerous error case where deletion is called accidentally without providing a condition, the use of the delete method without a specific condition is forbidden.

Instead, the distinct method truncate is provided to delete all records in a table with specific intent.

Returns true, or throws an exception on error.

  if ( $object->name ) {
      print "Object has been inserted\n";
  } else {
      print "Object has not been inserted\n";
  }

Returns true, or throws an exception on error.

REMAINING ACCESSORS TO BE COMPLETED

The last_position_in_file table was originally created with the following SQL command.

  CREATE TABLE last_position_in_file (
      name varchar(255) not null primary key,
      position integer not null
  )

Padre::DB::LastPositionInFile is part of the Padre::DB API.

See the documentation for Padre::DB for more information.

Adam Kennedy <adamk@cpan.org>

Copyright 2008-2011 The Padre development team as listed in Padre.pm.

This program is free software; you can redistribute it and/or modify it under the same terms as Perl itself.

The full text of the license can be found in the LICENSE file included with this module.