Does uno support x:Bind method invocation for private members ?

[jeromelaban]

Question from Emma111#5878 on Discord:

Hi, not sure this quite fits the github comment chain, a few questions

Does Uno support:

Child="{x:Bind m_viewFactory.CreateView(m_viewModel.PaneViewType), Mode=OneWay}"

where m_viewFactory and m_viewModel are private members of the UserControl?

Debugger shows that Uno does register a handler for m_viewModel.PaneViewType and it is invoked. However, CreateView is never called from Uno.

Currently isolating this section into it's own small test project

[jeromelaban]

Private members binding is supported, as well as invocation in methods, but there is a difference with the way WinUI works, seen in #2872. It may be that you're setting m_viewModel too late for the changes to be picked up the Uno's binding engine.

[jeromelaban]

Thanks. Would you be able to create a standalone repro of this behavior? Also, can you try doing something like this:

<StackPanel>
   <TextBlock Text="{x:Bind m_viewFactory, Mode=OneWay}" />
   <TextBlock Text="{x:Bind m_viewModel.PaneViewType, Mode=OneWay}" />
</StackPanel>

And see if what you get in the TextBlocks, visually?

[Rybasum]

@jeromelaban Does it matter that the getter of PaneViewType is implemented explicitly (through IDevicesPageVm) rather that being public? I remember that this used to be an issue in early UWP until Microsoft fixed it...

[jeromelaban]

@Rybasum it's not supposed to be an issue. Let me know what you see with the two TextBlock above, it may help find the root cause (aside from an actual standalone repro).

[jeromelaban]

The issue here is access to members on the bound types. The current implementation of x:Bind does not allow for binding on members this way, and requires members to be public on the actual instance being bound.

The workaround here is to do this:

public ViewType PaneViewType { set => SetAndNotify(ref m_paneViewType, value); get => m_paneViewType; }

to both have a getter and have PaneViewType being public.

Let's track this in #9539

[Tapir28]

This solved the issue, thank you!

[Tapir28]

Yep, I'll put it in a Repo, thanks!

[Tapir28]

https://github.com/Tapir28/TestMacFunctionBinding

Standalone repo of the issue.

On windows, Both textboxes work, as well as the ViewFactory.
On Mac however, none of them seem to.
TestMacFunctionBinding.zip

[Tapir28]

Just realised I replied to myself, so u might not have gotten a notification @jeromelaban apologies if you did already recieve one.