Question

I have a data object that has many different List properties. I want to use a single AddObject command instead of creating a different command for each List, so came up with the following code.

Is there any downsides you can see to using this? I thought performance might be slow, but I honestly haven’t seen a difference.

public MyViewModel()
{ 
    _addCommand = new RelayCommand<IEnumerable>(AddGenericObject);

    // Old code.... defines an Add command per list
    // _addAddressCommand = new RelayCommand(() => AddObject<Address>(AddressList));
    // _addPhoneCommand = new RelayCommand(() => AddObject<Phone>(PhoneList));
    // ... etc
}

private void AddGenericObject(IEnumerable list)
{
    // Find Add Method
    var addMethod = this.GetType()
        .GetMethod("AddObject", BindingFlags.NonPublic | BindingFlags.Instance);

    // Created Generic Add Method
    Type genericType = list.GetType().GetGenericArguments()[0];
    var genericAddMethod = addMethod.MakeGenericMethod(genericType);

    // Invoke Method
    genericAddMethod.Invoke(this, new object[] { list });
}

private void AddObject<T>(EntityCollection<T> list)
   where T : EntityObject, new()
{
    var newItem = new T();
    list.Add(newItem);
}

It is used in the XAML by something like this:

<Button Content="New Address" 
        Command="{Binding AddCommand}"
        CommandParameter="{Binding AddressList}" />

<Button Content="New Phone" 
        Command="{Binding AddCommand}"
        CommandParameter="{Binding PhoneList}" />

Answer 1

In one word – performance, but before you rid of the code benchmark it – it might be fast enough for your needs.