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Dave Rolsky > File-ChangeNotify > File::ChangeNotify::Watcher



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Module Version: 0.28   Source  


File::ChangeNotify::Watcher - Role consumed by all watchers


version 0.28


    my $watcher =
            ( directories => [ '/my/path', '/my/other' ],
              filter      => qr/\.(?:pm|conf|yml)$/,
              exclude     => ['t', 'root', qr(/(?!\.)[^/]+$),
                              sub { -e && ! -r }],

    if ( my @events = $watcher->new_events() ) { ... }

    # blocking
    while ( my @events = $watcher->wait_for_events() ) { ... }


A File::ChangeNotify::Watcher monitors a directory for changes made to any file. You can provide a regular expression to filter out files you are not interested in. It handles the addition of new subdirectories by adding them to the watch list.

Note that the actual granularity of what each watcher class reports may vary. Implementations that hook into some sort of kernel event interface (Inotify, for example) have much better knowledge of exactly what changes are happening than one implemented purely in userspace code (like the Default class).

By default, events are returned in the form of File::ChangeNotify::Event objects, but this can be overridden by providing an "event_class" attribute to the constructor.

The watcher can operate in a blocking/callback style, or you can simply ask it for a list of new events as needed.



This method creates a new watcher. It accepts the following arguments:


This method causes the watcher to block until it sees interesting events, and then return them as a list.

Some watcher subclasses may implement blocking as a sleep loop, while others may actually block.


This method returns a list of any interesting events seen since the last time the watcher checked.


If this is true, the watcher will report on all events.

Some watchers, like the Default subclass, are not smart enough to track things like a file being created and then immediately deleted, and can only detect changes between snapshots of the file system.

Other watchers, like the Inotify subclass, see all events that happen and report on them.


Bugs may be submitted at or via email to

I am also usually active on IRC as 'autarch' on irc://


The source code repository for File-ChangeNotify can be found at


Dave Rolsky <>


This software is Copyright (c) 2009 - 2018 by Dave Rolsky.

This is free software, licensed under:

  The Artistic License 2.0 (GPL Compatible)

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

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