# phpman > man > Cache::Entry(3pm)

## NAME
    [Cache::Entry](https://www.chedong.com/phpMan.php/perldoc/Cache%3A%3AEntry/markdown) - interface for a cache entry

## SYNOPSIS
      my [Cache::Entry](https://www.chedong.com/phpMan.php/perldoc/Cache%3A%3AEntry/markdown) $entry = $cache->entry( $key )
      my $data;
      if ($entry->exists()) {
          $data = $entry->get();
      }
      else {
          $data = get_some_data($key);
          $entry->set($data, '10 minutes');
      }

## DESCRIPTION
    Objects derived from [Cache::Entry](https://www.chedong.com/phpMan.php/perldoc/Cache%3A%3AEntry/markdown) represent an entry in a Cache. Methods are provided that act
    upon the data in the entry, and allow you to set things like the expiry time.

    Users should not create instances of [Cache::Entry](https://www.chedong.com/phpMan.php/perldoc/Cache%3A%3AEntry/markdown) directly, but instead use the entry($key)
    method of a Cache instance.

## METHODS
    my $cache = $e->cache()
        Returns a reference to the cache object this entry is from.

    my $key = $e->key()
        Returns the cache key this entry is associated with.

    my $bool = $e->exists()
        Returns a boolean value (1 or 0) to indicate whether there is any data present in the cache
        for this entry.

    $e->set( $data, [ $expiry ] )
        Stores the data into the cache. The data must be a scalar (if you want to store more complex
        data types, see freeze and thaw below).

        The expiry time may be provided as an optional 2nd argument and is in the same form as for
        'set_expiry($time)'.

    my $data = $e->get()
        Returns the data from the cache, or undef if the entry doesn't exist.

    my $size = $e->size()
        Returns the size of the entry data, or undef if the entry doesn't exist.

    $e->remove()
        Clear the data for this entry from the cache.

    my $expiry = $e->expiry()
        Returns the expiry time of the entry, in seconds since the epoch.

    $e->set_expiry( $time )
        Set the expiry time in seconds since the epoch, or alternatively using a string like '10
        minutes'. Valid units are s, second, seconds, sec, m, minute, minutes, min, h, hour, hours,
        w, week, weeks, M, month, months, y, year and years. You can also specify an absolute time,
        such as '16 Nov 94 22:28:20' or any other time that [Date::Parse](https://www.chedong.com/phpMan.php/perldoc/Date%3A%3AParse/markdown) can understand. Finally, the
        strings 'now' and 'never' may also be used.

    my $fh = $e->handle( [$mode, [$expiry] ] )
        Returns an [IO::Handle](https://www.chedong.com/phpMan.php/perldoc/IO%3A%3AHandle/markdown) by which data can be read, or written, to the cache. This is useful if
        you are caching a large amount of data - although it should be noted that only some cache
        implementations (such as [Cache::File](https://www.chedong.com/phpMan.php/perldoc/Cache%3A%3AFile/markdown)) provide an efficient mechanism for implementing this.

        The optional mode argument can be any of the perl mode strings as used for the open function
        '<', '+<', '>', '+>', '>>' and '+>>'. Alternatively it can be the corresponding [fopen(3)](https://www.chedong.com/phpMan.php/man/fopen/3/markdown)
        modes of 'r', 'r+', 'w', 'w+', 'a' and 'a+'. The default mode is '+<' (or 'r+') indicating
        reading and writing.

        The second argument is used to set the expiry time for the entry if it doesn't exist already
        and the handle is opened for writing. It is also used to reset the expiry time if the entry
        is truncated by opening in the '>' or '+>' modes. If the expiry is not provided in these
        situations then the default expiry time for the cache is applied.

        Cache implementations will typically provide locking around cache entries, so that writers
        will have have an exclusive lock and readers a shared one. Thus the method get() (or
        obtaining another handle) should be avoided whilst a write handle is held. Using set() or
        remove(), however, should be supported. These clear the current entry and whilst they do not
        invalidate open handles, those handle will from then on refer to old data and any changes to
        the data will be discarded.

## STORING VALIDITY OBJECTS
    There are two additional set & get methods that can be used to store a validity object that is
    associated with the data in question. Typically this is useful in conjunction with a
    validate_callback, and may be used to store a timestamp or similar to validate against. The
    validity data stored may be any complex data that can be serialized via Storable.

    $e->validity()
    $e->set_validity( $data )

## STORING COMPLEX OBJECTS
    The set and get methods only allow for working with simple scalar types, but if you want to
    store more complex types they need to be serialized first. To assist with this, the freeze and
    thaw methods are provided. They are simple wrappers to get & set that use Storable to do the
    serialization and de-serialization of the data.

    Note, however, that you must be careful to ONLY use 'thaw' on data that was stored via 'freeze'.
    Otherwise the stored data wont actually be in Storable format and it will complain loudly.

    $e->freeze( $data, [ $expiry ] )
        Identical to 'set', except that data may be any complex data type that can be serialized via
        Storable.

    $e->thaw()
        Identical to 'get', except that it will return a complex data type that was set via
        'freeze'.

## SEE ALSO
    Cache, [Cache::File](https://www.chedong.com/phpMan.php/perldoc/Cache%3A%3AFile/markdown)

## AUTHOR
     Chris Leishman <<chris@leishman.org>>
     Based on work by DeWitt Clinton <<dewitt@unto.net>>

## COPYRIGHT
     Copyright (C) 2003-2006 Chris Leishman.  All Rights Reserved.

    This module is distributed on an "AS IS" basis, WITHOUT WARRANTY OF ANY KIND, either expressed
    or implied. This program is free software; you can redistribute or modify it under the same
    terms as Perl itself.

    $Id: Entry.pm,v 1.8 2006/01/31 15:23:58 caleishm Exp $