🧪 [Experiment] DependencyPropertyGenerator

[Sergio0694]

Note

Originally from #449.

Overview

Tracking issue for the new DependencyProperty generator, for UWP (both .NET Native and .NET 9) and WinUI 3.
This is what using the new generator looks like:

[GeneratedDependencyProperty]
public string? Name { get; set; }

It only supports instance properties. Attached properties are not currently supported.

Remaining task

Here's a few remaining tasks to track work:

• Codegen for DefaultValueCallback
• Improve formatting for PropertyMetadata construction
• Diagnostic for using DefaultValue and DefaultValueCallback at the same time
• Diagnostic for DefaultValueCallback set to null
• Diagnostic for DefaultValueCallback not matching an existing method
• Diagnostic for DefaultValueCallback matching an invalid method (eg. wrong signature)
• Diagnostic for properties that end with the "Property" suffix

[insomniachi]

Why was the name of the attribute changed from DependencyPropertyAttribute to GeneratedDepedencyPropertyAttribute?
it causes some conflict with existing DependencyProperty class?
we don't have the word Generated in ObservablePropertyAttribute

[michael-hawker]

@insomniachi see the comment here: #617 (comment)

In theory we could name it the same, it wouldn't conflict because it's an attribute. But in general, the convention is to use the "Generated" prefix for attributes triggering generation (eg. see [GeneratedComInterface], GeneratedComClass], [GeneratedRegex], etc.). If anything, it's the attributes in the MVVM Toolkit that are kinda breaking this 😅