Explain what this mean in C#?

Question

NotifyOfPropertyChange<ObservableCollection<BaseMdmViewModelCollection>>(() => SubItemsViewModels);

Answer 1

It's making a call to a generic function with signature

NotifyOfPropertyChange<T>(Func<BaseMdmViewModelCollection>)

() => SubItemsViewModels

is identical to

delegate { return SubItemsViewModels; }

In other words,

NotifyOfPropertyChange<ObservableCollection<BaseMdmViewModelCollection>>(() => SubItemsViewModels);

is the same as

NotifyOfPropertyChange<ObservableCollection<BaseMdmViewModelCollection>>(Foo);

where Foo would be

private BaseMdmViewModelCollection Foo()
{
    return SubItemsViewModels;
}

Answer 2

简而言之：当可观察的集合发生变化时，返回Sub items视图模型。

Answer 3

I'd be willing to bet that your NotifyOfPropertyChange method is using the Func to simply get the name of the property that changed. This gives you compile-time safety of property changes, which is much more preferable than saying NotifyPropertyChange("SubItemsViewModels") . This approach is used extensively in WPF and Silverlight data bindings, but is also a general purpose pattern that is useful in many scenarios.

Answer 4

You have a method NotifyOfPropertyChange(Func func), where in your case T1 is BaseMdmViewModelCollection.

SubItemsViewModels is from type ObservableCollection

This is a way to pass any function that returns the collection instead of passing the collection directly.

Cheers,

Gilad