ObservableProperty should support lazy initialization. #136
Description
Describe the problem
ObservableProperty right now doesnt provide a way to initialize property or lazy initialize the properties. So in case where we need that we have to manually do that in the constructor.
Example
Following is a property (along with backing field) with traditional mvvm way and I am including lazy initialization in it so that this object will never be null when app wants to use it.
private DropDownsVM _dropDowns;
public DropDownsVM DropDowns { get => _dropDowns ??= new DropDownsVM(); set => SetProperty(ref _dropDowns, value); }
Now when I wanna use ObservableProperty annotation from Microsoft.Toolkit.Mvvm.ComponentModel I do the following way and have to add initialization in constructor.
public AppViewModel()
{
DropDowns = new DropDownsVM();
}
[ObservableProperty]
private DropDownsVM dropDowns;
Describe the solution
Ideally there should be a way to indicate that property should autogenerate the lazy initialization or atleast normal initialization.
Maybe Something like this
[ObservableProperty(new(), true)]
private DropDownsVM dropDowns;
[ObservableProperty(new(123), true)]
private DropDownsVM dropDowns;
in the first example [ObservableProperty(new(), true)] takes 2 parameters, first one being the automatic constructor of the object using latest c# language so we dnt have to write new DropDownsVM() fully, the 2nd parameter is a boolean indicating whether LazyInitialization=true
2nd example is same as first, only in this case we are providing a different constructor for the object and that constructor takes a parameter int, which is in this case 123 this lets us do all kind of initializations of the property right within the annotation and will reduce code a lot I think.
This could also work for other kinds of nonNullable objects i.e : providing a default value for a boolean or string etc.
Alternatives
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Additional info
Package version : Microsoft.Toolkit.Mvvm (7.1.2)
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