Question: Use async function in Python programs

[ghost]

Hi there,

There is a lack of documentation and examples on the use of async function for the python bindings. As i don't find any solution, i think it's better to ask directly. Anyway, i don't think I'm alone in this case.

For my project, i use PackageKit v1.0 python bindings. In order to have a non blocking refresh cache or install software operation, i use the native Thread class from python libs. But, as far as i know _async methods in PKit work properly, but i don't know how to achieve my goal.

With two callbacks declared : one follows PackageKitGlib.ProgressCallback signature and the other one follow Gio.AsyncReadyCallback

• For PackageKitGlib.ProgressCallback

    def transmit_repository_update_status(self, progress, type, user_data):
        self.panel.set_repository_update_status(progress.props.percentage)

• For Gio.AsyncReadyCallback

    def async_ready(self, source, res, data):
        print(str(source) + str(res) + str(data))

The function call is :

self.refresh_cache_async(False, self.canceller, callback_update_repository, None, 
async_ready, None)

The result is a TypeError: expected tuple for callback user_data exception. As far as i know, i can't understand why.

After searching for a solution of the web since a couple of month, i gave up and still used native threads. But this is not a good solution.

Can you provide an example for this kind of problem or anything else that can help the developers ?
Anyway, does this question will have to be asked to the mailling list of developers that maintain the bindings ?

[hughsie]

I think the mailing list is a much better place to ask these kind of questions; I'm not a huge python guru so I'm not sure how you'd handle that vfunc progress callback. My gut instinct is the scope attributes are wrong, but I'm not sure.

[ximion]

You should do something like this:

pktask.refresh_cache_async (False, # force
                                            None,  # GCancellable
                                            self.on_pktask_progress,
                                            (None,), # user data
                                            self.on_pktask_finish,
                                            (None,));

This is not a PackageKit issue, rather a PyGObject weirdness.

[ghost]

Ok thanks a lot, I'll try to write a script and publish it. :)