Re: Getting the result of a DBus method call.

["Jasper St. Pierre" <jstpierre mecheye net>]

Use "Sync" instead of "Remote". Note that if the DBus call takes a
long time, this will freeze the Shell, so consider using Remote by
restructuring your code:

    dbusProxy.<methodname>Remote(/* arguments ... */, function (result) {
        // Continue your code here, rather than below the DBus call.
    });

For your information, this style of code is called "continuation
passing", and it can get unwieldy very quickly as your callbacks pile
up. In future versions of ECMAScript, they'll allow things called
Promises, so you can do:

    let promise = dbusProxy.<methodname>Remote(/* arguments ... */);
    promise.addCallback(function(result) {
        // Continue your code here, rather than than below the DBus call.
    });

Although this may not seem like such a big change, given that promises
are like any other object, you can return a promise instead of having
to take callbacks as arguments to be passed all the way down the
chain.

Also, trampolines:

    yield let result = dbusProxy.<methodname>Remote(/* arguments ... */);

On Thu, Oct 4, 2012 at 2:40 AM, Amy <mathematical coffee gmail com> wrote:
> Hi all,
>
> I'm taking first steps learning how to use DBus in a gnome shell extension.
>
> I've hit a stumbling block - how do I get the result of a remote
> method immediately?
>
> Something like:
>
>    let value = dbusProxy.<methodname>Remote(/* arguments ... */,
> function (result) { ???? how to return it???? });
>
> In the usage above, I want the `result` in the callback to be assigned
> to value so that if my next line of code is (say)
>
>     log(value);
>
> this will be up-to-date.
>
> Otherwise, I could do something like:
>
>     let value;
>     dbusProxy.<methodname>Remote(/* arguments ... */, function
> (result) { value = result; });
>     log(value);
>
> but when I do this, 'value' is not up to date (until the callback
> completes), so I can't rely on the above code if I want to use 'value'
> straight away.
>
> Is there some way around this?
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-- 
  Jasper