.NET MAUI 9: Compiled bindings

[davidbritch]

In .NET MAUI 9 there's a source generator that allows developers to call the SetBinding extension method to define bindings on their bindable objects using Func instead of string paths. There's also an additional API that builds on this that will not only set the binding directly to the object, but it will return the binding object instance and allow the developer to pass it to some other method and use it later.

This approach is required instead of string-based bindings in NativeAOT apps, and in apps with full trimming enabled.

String-based binding in code:

label.BindingContext = new PageViewModel { Customer = new CustomerViewModel { Name = "John" } };
label.SetBinding(Label.TextProperty, "Customer.Name");

Compiled binding in code:

label.SetBinding<PageViewModel, string>(Label.TextProperty, static vm => vm.Customer.Name);
// or with type inference:
label.SetBinding(Label.TextProperty, static (PageViewModel vm) => vm.Customer.Name);

Compiled binding in XAML:

<Label Text="{Binding Customer.Name}" x:DataType="local:PageViewModel" />

Will also need to update the compiled bindings doc.

More info: dotnet/maui#23239

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Associated WorkItem - 314392