[Development] Start of a refactor of the QSettings class based on QJson

[Tomaz Canabrava]

On Thu, Sep 25, 2014 at 6:51 PM, Jeremy <jeremy.k.list at gmail.com> wrote:

>
> On 5September2014, at 12:33, Tomaz Canabrava <tcanabrava at kde.org> wrote:
>
> > Long that that I have send this e-mail already, but better late than
> never.
> > In the Qt Develompent Summit I raised my hand to get one dirty thing
> done:
> >
> > The Settings.
> >
>
> The general idea appeals to me.
>
>
> > After a good while with negative time ( Real Work, KDE, Subsurface, and
> other personal stuff ) I have finally had the time to start.
> >
> > For now, I'v implemented two things:
> >
> > Parsing from .ini to QJson
> > Saving from QJson to .ini
> >
> > Why .ini instead of json, since I'm doing a conversion and I coul'd
> simply store the json file?
> >
> > .ini is better to humanreadability.
> > thiago asked me to do from ini to qjson
>
>
> Binary compatibility requires that QSettings for 5.x continue to handle
> .ini files for all existing functions. Adding json for 5.5 should be fine.
>

I think we are talking different things here. the settings would continue
to be in .ini format, the json would be used as binary -cache ( disk and
memory ).


>
>
> >
> > Issues:
> >
> > After a Json tree is constructed, it's hard to modify it's contents:
> >
> > QJsonObject rootConfig;
> > rootConfig.insert("group1", QJsonObject());
> > rootConfig.insert("group2", QJsonObject());
> >
> > QJsonObject group1 = rootConfig.vaule("group1").toObject();
> > group1.insert("key1", 1);
> > rootConfig.insert("group1", group1);
> >
> > since I need to take the value, modify it, insert it back nested groups
> are a pain to use,
> > because I would have to chain the removal / addtion of the parent group
> untill I hit the rootGroup.
> >
>
> QJsonDocument doc = QJsonDocument::fromJson("{ \"name\": \"object\"}");
> QJsonObject obj = doc.object();
> QJsonValueRef ref = obj["name”];
> ref = "object2”;
> doc.setObject(obj);
>

QJsonObject obj = doc.object();
QJsonValueRef ref = obj["group1"];
QJsonObject groupObject = ref.toObject(); // <- lost reference.
QJsonValueRef ref2 = groupObject["group2];
QJsonObject groupObject2 = ref2.toObject(); << - again, lost reference.
groupObject2.add("key", object2);

and that's the issue.


>
>
> > what I plan to do, besides that:
> > - changed the config file from outside of the app, the app should reload
> it's settings.
>
>
> What’s the intended change detection mechanism? If it’s a file change,
> there’s the issue of incomplete updates to handle. I suppose it could
> ignore anything other than an valid JSON, empty files, and deleted files
> under the theory that edits of a single entry are less likely to produce
> valid interim results.
>

It will be a .ini file, so invalid json is a non issue, the others are, but
first I need to find a way to work around the other issue that I described.


> Will changes be announced at the document level, or more fine grained? I
> think anything beyond the document level is asking for trouble.
>

Document level.


>
> > - compile-time check of typos in keys based on a schema ( and not
> runtime. )
> >
> > Help is appreciated, and comments welcome.
> >
> > the *temporary* repo with the *temporary and somewhat broken* code:
> > github.com:tcanabrava/QConfigNG
> >
>
>
>
-------------- next part --------------
An HTML attachment was scrubbed...
URL: <http://lists.qt-project.org/pipermail/development/attachments/20141002/6f881bee/attachment.html>