[ovirt-devel] Type Safety on the Frontend (refactoring of all async queries)

[Vojtech Szocs]

Great work, Martin!

Always happy to see improvements in UI code :)

Vojtech


----- Original Message -----
> From: "Martin Betak" <mbetak at redhat.com>
> To: "devel" <devel at ovirt.org>
> Cc: "Vojtech Szocs" <vszocs at redhat.com>, "Tomas Jelinek" <tjelinek at redhat.com>, "Alexander Wels" <awels at redhat.com>
> Sent: Monday, July 25, 2016 8:54:39 PM
> Subject: Type Safety on the Frontend (refactoring of all async queries)
> 
> Hi All,
> 
> today a *major* frontend refactoring was merged [1].
> Its purpose was to remove some of the most significant artifacts of legacy C#
> code.
> 
> Huge thanks to Vojtech and Alex for heavenly patience during code review!
> 
> For a complete description please see the commit message, but here are
> some highlights for programmers that need to touch FE code:
> 
> 1) AsyncQuery, AsyncCallback and Converter are now generic and typesafe
>    (formerly INewAsyncCallback and IAsyncConverter).
> 
> 2) It is no longer possible (or desirable) to PASS MODEL to queries.
>    From within Model sublasses `new AsyncQuery<>(...)` will have the correct
>    value set
>    (see patch for impl details) and if you want to run a query on a different
>    model
>    (so the infrastructure would set the progress spinner on that model
>    instead),
>    usually for the purpose of a ListModel showing a popup window - where we
>    want to
>    display the spinner on the dialog window instead, you can use the
>    `myWindowModel.asyncQuery(...)` helper factory to create query with model
>    set
>    to myWindowModel.
> 
>    // note: this also has the nice side-effect of eliminating the harmful
>    pattern of using
>    // the model value from within callbacks by casting it to surrounding
>    model type (while that
>    // value is already available by feature of java inner classes)
> 
> 3) AsyncDataProvider's API methods now deal with strongly typed queries. This
> is facilitated
>    through usage of strongly typed Converters (please see some defined
>    converters -> usually
>    you just need a CastingConverter<> or a ListConverter<>).
>    Please use this architectural layer of strongly typed AsyncDataProvider to
>    your advantage.
>    (as plain  Fronted.runQuery does not provide any guarantees and leaves you
>    at risk of
>    mis-casting the return value).
> 
> If you have any more questions please feel free to ask me or look at the
> patch for details
> (warning: it's quite big!).
> 
> This kind of major change necessarily touched all areas of the code (those
> issuing queries...)
> and there is of course some probability that something may break. But I
> believe this risk is
> well outweight by the benefits. Nevertheless if you find any issue please let
> me know and
> we can fix it together.
> 
> Thanks again to anyone who contributed to this noble effort.
> 
> Best regards :-)
> 
> Martin
> 
> [1] https://gerrit.ovirt.org/#/c/60822/
>