[Interest] QSettings watching for updates.

[pritam....@gmail.com]

Hi

I am using QSettings for persistent settings in my application. These settings may be modified by some other processes at runtime.

I need some notification when this happens. I looked at QSettings API, couldn't find any such notification mechanism. 

Is there any mechanism for this. I was trying to avoid QFileSystemWatcher.

--
pritam

[Jason H]

You should just have an object that manages your settings then. When it writes something, just emit your signal.

It would have a QSettings member, or derive from QSettings.

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From: "pritam....@gmail.com" <pritam....@gmail.com>
To: inte...@qt-project.org
Sent: Monday, January 9, 2012 12:25 PM
Subject: [Interest] QSettings watching for updates.

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Inte...@qt-project.org
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[Alan Ezust]

Qt Mobility has a publish-subscribe module which is basically like QSettings but with IPC in mind.
It already has the ability to notify you of changes.

http://doc.qt.nokia.com/qtmobility/publ-subs.html

[Till Oliver Knoll]

Am 21.01.2012 um 15:32 schrieb Alan Ezust <alan....@gmail.com>:

> Qt Mobility has a publish-subscribe module which is basically like QSettings but with IPC in mind.
> It already has the ability to notify you of changes.

If "immediate notifications" are not a must, then "polling for changes" might also be a possibility: re-loading the QSettings every n minutes (or seconds).

Cheers, Oliver

[Jason H]

I'd just suggest the QFileSystem watcher with a file (won't work with Windows registry QSettings)

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From: Till Oliver Knoll <till.oli...@gmail.com>
To: "inte...@qt-project.org" <inte...@qt-project.org>
Sent: Monday, January 23, 2012 6:18 AM
Subject: Re: [Interest] QSettings watching for updates.

[Scott Aron Bloom]

Hoever, it would NOT be hard to extend FileSystemWatcher to handle watching the registry.

Similar Win32 messages are emitted when the portion of the registry changes and you are watching that portion..

Scott

[Jason H]

Yes, but that would not be portable. However you can force QSettings to use another storage medium. (i.e. a file) which would be portable and transparent.

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From: Scott Aron Bloom <Scott...@onshorecs.com>
To: Jason H <scor...@yahoo.com>; Till Oliver Knoll <till.oli...@gmail.com>; inte...@qt-project.org
Sent: Monday, January 23, 2012 3:01 PM
Subject: RE: [Interest] QSettings watching for updates.

[Scott Aron Bloom]

That’s my point…

 

QSettingsWatcher for windows would have to be a variant but non-portable enhancement to QFileWatcher..

 

However, QSettingsWatcher for Linux could BE QFileWatcher, just pointing to each file/directory.

 

For mac, Im not sure if it uses pfile or not, but again, pretty easy to watch.

 

Scott

[Till Oliver Knoll]

Am 23.01.2012 um 18:12 schrieb "Scott Aron Bloom" <Scott...@onshorecs.com>:

For mac, Im not sure if it uses pfile or not, but again, pretty easy to watch.

If not specified otherwise the format is the "native" plist file format. You can also have INI files.

Both are plain files in any case.

While not against the idea at all to have a cross-platform "settings watcher" I wonder how many applications out there do have their settings changed from another process (well, at least one, that's for sure ;))

Cheers, Oliver