File::Monitor::Object(3)

NAME
File::Monitor::Object - Monitor a filesystem object for changes.

VERSION
This document describes File::Monitor::Object version 1.00

SYNOPSIS
Created by File::Monitor to monitor a single file or directory.

    use File::Monitor;
    use File::Monitor::Object;

    my $monitor = File::Monitor->new();

    for my $file ( @files ) {
        $monitor->watch( $file );
    }

    # First scan just finds out about the monitored files. No changes
    # will be reported.
    $monitor->scan;

    # Later perform a scan and gather any changes
    for my $change ( $monitor->scan ) {
        # $change is a File::Monitor::Delta
    }

DESCRIPTION
Monitors changes to a single file or directory. Don't create a "File::Monitor::Object" directly; instead call "watch" on File::Monitor.

A "File::Monitor::Object" represents a single file or directory. The corresponding file or directory need not exist; a file being created is one of the events that is monitored for. Similarly if the file or directory is deleted that will be reported as a change.

Changes of state are returned as a File::Monitor::Delta object.

The state of the monitored file or directory at the time of the last "scan" can be queried. Before "scan" is called these methods will all return "undef". The following methods return the value of the corresponding field from "stat" in perlfunc:

    dev inode mode num_links uid gid rdev size
    atime mtime ctime blk_size blocks

For example:

    my $file_size = $object->size;
    my $modified  = $object->mtime;

If any error occured during the previous "scan" it may be retrieved like this:

    my $last_error = $obj->error;

It is not an error for the file being monitored not to exist.

Finally if a directory is being monitored and the "files" or "recurse" option was specified the list of files in the directory may be retrieved like this:

    my @contained_files = $obj->files;

If "files" was specified this will return the files and directories immediately below the monitored directory but not the contents of any subdirectories. If "recurse" was specified the entire directory tree below this directory will be returned.

In either case the returned filenames will be complete absolute paths.

  Caveat for Directories
Note that "File::Monitor::Object" has no magical way to quickly perform a recursive scan of a directory. If you point it at a directory containing 1,000,000 files and specify the "recurse" option directory scans will take a long time.

INTERFACE

"new( $args )"
    Create a new "File::Monitor::Object". Don't call "new" directly; use instead File::Monitor->watch.

"scan()"
    Perform a scan of the monitored file or directory and return a list of changes. The returned list will contain either a single File::Monitor::Delta object describing all changes or will be empty if no changes occurred.

        if ( my $change = $object->scan ) {
            # $change is a File::Monitor::Delta that describes all the
            # changes to the monitored file or directory.
        }

    When "scan" is first called the current state of the monitored file/directory will be captured but no change will be reported.

"callback( [ $event, ] $coderef )"
    Register a callback. If $event is omitted the callback will be called for all changes. Specify $event to limit the callback to certain event types. See File::Monitor::Delta for a full list of events.

        $object->callback( sub {
            # called for all changes
        } );

        $object->callback( metadata => sub {
            # called for changes to file/directory metatdata
        } );

    See File::Monitor::Delta for a full list of events that can be monitored.

"name"
    Returns the absolute name of the file or directory being monitored. If "new" was passed a relative path it is resolved relative to the current directory at the time of object creation to make it absolute.

"files"
    If monitoring a directory and the "recurse" or "files" options were specified to "new", "files" returns a list of contained files. The returned filenames will be absolute paths.

  Other Accessors
In addition to the above the following methods may be called to return the value of the corresponding field from "stat" in perlfunc:

    dev inode mode num_links uid gid rdev size
    atime mtime ctime blk_size blocks

For example:

    my $inode = $obj->inode;

Check the documentation for "stat" in perlfunc to discover which fields are valid on your platform.

DIAGNOSTICS

"%s is read-only"
    You have attempted to modify a read-only accessor. It may be tempting for example to attempt to change the name of the monitored file or directory like this:

        # Won't work
        $obj->name( 'somefile.txt' );

    All of the attributes exposed by "File::Monitor::Object" are read-only.

"When options are supplied as a hash there may be no other arguments"
    When creating a new "File::Monitor::Object" you must either supply "new" with a reference to a hash of options or, as a special case, pass a filename and optionally a callback.

"The name option must be supplied"
    The options hash must contain a key called "name" that specifies the name of the file or directory to be monitored.

"A filename must be specified"
    You must suppy "new" with the name of the file or directory to be monitored.

CONFIGURATION AND ENVIRONMENT
File::Monitor::Object requires no configuration files or environment variables.

DEPENDENCIES
None.

INCOMPATIBILITIES
None reported.

BUGS AND LIMITATIONS
No bugs have been reported.

Please report any bugs or feature requests to "bug-file-monitor@rt.cpan.org", or through the web interface at <http://rt.cpan.org>.

AUTHOR
Andy Armstrong "<andy@hexten.net>"

Faycal Chraibi originally registered the File::Monitor namespace and then kindly handed it to me.

LICENCE AND COPYRIGHT
Copyright (c) 2007, Andy Armstrong "<andy@hexten.net>". All rights reserved.

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

DISCLAIMER OF WARRANTY
BECAUSE THIS SOFTWARE IS LICENSED FREE OF CHARGE, THERE IS NO WARRANTY FOR THE SOFTWARE, TO THE EXTENT PERMITTED BY APPLICABLE LAW. EXCEPT WHEN OTHERWISE STATED IN WRITING THE COPYRIGHT HOLDERS AND/OR OTHER PARTIES PROVIDE THE SOFTWARE "AS IS" WITHOUT WARRANTY OF ANY KIND, EITHER EXPRESSED OR IMPLIED, INCLUDING, BUT NOT LIMITED TO, THE IMPLIED WARRANTIES OF MERCHANTABILITY AND FITNESS FOR A PARTICULAR PURPOSE. THE ENTIRE RISK AS TO THE QUALITY AND PERFORMANCE OF THE SOFTWARE IS WITH YOU. SHOULD THE SOFTWARE PROVE DEFECTIVE, YOU ASSUME THE COST OF ALL NECESSARY SERVICING, REPAIR, OR CORRECTION.

IN NO EVENT UNLESS REQUIRED BY APPLICABLE LAW OR AGREED TO IN WRITING WILL ANY COPYRIGHT HOLDER, OR ANY OTHER PARTY WHO MAY MODIFY AND/OR REDISTRIBUTE THE SOFTWARE AS PERMITTED BY THE ABOVE LICENCE, BE LIABLE TO YOU FOR DAMAGES, INCLUDING ANY GENERAL, SPECIAL, INCIDENTAL, OR CONSEQUENTIAL DAMAGES ARISING OUT OF THE USE OR INABILITY TO USE THE SOFTWARE (INCLUDING BUT NOT LIMITED TO LOSS OF DATA OR DATA BEING RENDERED INACCURATE OR LOSSES SUSTAINED BY YOU OR THIRD PARTIES OR A FAILURE OF THE SOFTWARE TO OPERATE WITH ANY OTHER SOFTWARE), EVEN IF SUCH HOLDER OR OTHER PARTY HAS BEEN ADVISED OF THE POSSIBILITY OF SUCH DAMAGES.