Overview

This issue is meant to be used to track all the feature requests and discussions regarding API changes or other tweaks for the Microsoft.Toolkit.Mvvm package, which was introduced with #3230 and recently announced. 🎉

Find initial docs and samples here at https://aka.ms/mvvmtoolkit.

Key Tenants

• Platform and Runtime Independent - .NET Standard 2.0 🚀 (UI Framework Agnostic)
• Simple to pick-up and use - No strict requirements on Application structure or coding-paradigms (outside of 'MVVM'ness) i.e. flexible usage
• À la carte - Developer able to choose the components they wish to leverage
• Reference Implementation - Lean and performant, provides compliments to interfaces and paradigms hinted at in the Base-Class Library, but without provided implementations.

If you want more info on the package, you're welcome to browse our samples and preview documentation (here), watch the initial presentation by @michael-hawker and I (here) or watch Michael's presentation during the UNO Conf (here).

Tracking changes so far

Will be updating this list with all the current (work in progress) changes that are being included into a PR.

Preview 5 (#3562)

• Added ObservableValidator.ClearErrors method
• Added ObservableValidator.ValidateProperty method
• Added ObservableValidator.ValidateAllProperties method
• Added generic ObservableValidator.GetErrors method
• Speed/memory optimizations to WeakReferenceMessenger on .NET Standard 2.0

Preview 4 (#3527)

• Reintroduced Ioc class (see docs)
• Added new ObservableObject.OnPropertyChanged(PropertyChangedEventArgs) overload
• Added new ObservableObject.OnPropertyChanging(PropertyChangingEventArgs) overload
• The OnPropertyChanged and OnPropertyChanging overloads with a string param are no longer virtual
• Added notification support to IAsyncRelayCommand.CanBeCanceled property
• Improved notification logic for other IAsyncRelayCommand properties
• Added notification support to ObservableValidator.HasErrors property
• Added new TrySetProperty methods to ObservableValidator
• Minor performance/memory usage improvements and bug fixes

Preview 3 (shipped!) 🚀

ComponentModel, Input, DependencyInjection (#3429)

• New ObservableValidator class for INotifyDataErrorInfo
• Changed SetPropertyAndNotifyOnCompletion signature (7-14x faster, 60% memory usage reduction)
• Changed signature of APIs, ditched Expression<Func<T>> args
• Added new SetProperty<T, TModel> overload to allow stateless delegates and better performance
• Added cancelation support to AsyncRelayCommand types (and interfaces)
• Improved XML docs with info about exceptions being thrown by the various APIs
• Removed Ioc class and Microsoft.Extensions.DependencyInjection dependency

Messenger (#3424)

• Added a new WeakReferenceMessenger type
• Renamed Messenger to StrongReferenceMessenger
• Memory usage and performance improvements to StrongReferenceMessenger
• Changed IMessenger.Register signature to remove closures (35% memory usage reduction, no this captured)
• Added IMessenger.Cleanup API to help with extensibility
• Changed default messenger for ObservableRecipient to WeakReferenceMessenger