Question

Is there a difference between this two variants (performance, memory leaks or guidelines)?

With NPC:

private ICommand mGoBackCommand;

    public ICommand GoBackCommand
    {
        get { return mGoBackCommand; }
        set
        {
            if (mGoBackCommand != value)
            {
                mGoBackCommand = value;
                RaisePropertyChanged("GoBackCommand");
            }
        }
    }

Auto property:

public ICommand GoBackCommand {get; set;}

UPD:
Final question is:
Can I use auto properties in VievModel if they are simple commands which will be assigned once in constructor, or I need implement NPC on each property of the VM because of performance, memory leaks or something else?

Answer 1

If you are writing a class that implements INotifyPropertyChanged, you are making a contract that says “I’ll raise the PropertyChanged event when any property changes.”

But, if you know for a fact that a property won’t change during the lifetime of the instance, then you trivially satisfy that contract by never raising PropertyChanged for that property.

So, if you set a property once in the constructor (a “set it a forget it” property), then you don’t need to mangle the property just to support INotifyPropertyChanged and you can use an auto-implemented property. However, in this you should change the property from this:

public ICommand GoBackCommand { get; set; }

to this:

public ICommand GoBackCommand { get; private set; }

so that it cannot be accidentally modified outside the class.