We agreed to implement a new public API to allow creating "compiled" bindings (TypedBinding<TSource, TProperty>) in code via source-generators and interceptors based on the proposal #20574 (see Alternative design).

• Introduce new public method BindableObjectExtensions.SetBinding<TSource, TProperty>(BindableProperty property, Func<TSource, TProperty> getter, ...) as defined in the proposal
• Create a new source generator
  • Intercept calls to SetBinding<TSource, TProperty>(...)
  • Parse getter lambda expression
    • Implement support for properties
    • Implement support for indexers
    • Implement support for as-casts
    • Implement support for C-style casts
    • Implement support for conditional access to members
    • Implement diagnostics reporting
    • Build cacheable data model
  • Generate setter from the getter lambda
  • Generate handlers array from the getter lambda
• Enable the source generator by default in MAUI apps
  • Introduce a feature switch to disable the source generator
• Add unit tests for correct caching of the generated code
• Run benchmarks comparing reflection-based binding, source-generated binding, and hand-written typed binding
• Write docs/developer guide - tracked in .NET MAUI 9: Compiled bindings can be used with C# markup docs-maui#2304

Possible future improvements

• Replace usage of TypedBinding.ForSingleNestingLevel(...) with the source generated interceptors - [Binding SG] Dogfood binding source generator in the MAUI codebase #23393
• Implement support for generic parameters
• Use the new overload in existing unit tests
• Add more public methods that could be intercepted (this has not been discussed/agreed on yet) - [Binding SG] Add an API for creating instances of TypedBinding #23239
  • for example:
    • BindingBase Binding.Create<TSource, TProperty>(Func<TSource, TProperty> getter, ...)
    • TBindable Bind<TBindable, TSource, TProperty>(this TBindable bindableObject, Func<TSource, TProperty> getter, ...) where TBindable : BindableObject.
• Improve efficiency by grouping calls to SetBinding with the same getter signature into one interceptor
• Split individual generated methods into separate files for more granular caching - [Binding SG] Split bindings source generated code into multiple files #23116
• Explore the option of resolving method groups instead of just lambda expressions
• Use roslyn-sdk test library