Add IndexMove() to List

[zms9110750]

The effect is similar to

var temp = list[index];
list.RemoveAt(index);
list.Insert(newIndex, temp);

This operation will cause all subsequent projects after the affected project to move meaningless twice.
I hope he has his own API to achieve this more efficiently.

[huoyaoyuan]

For efficiency, you can use CollectionsMarshal.AsSpan to manipulate the backing storage yourself. The operation doesn't seem to be common.

[redflitzi]

Hm, a first step might be to invent for List <T>:

public T Detach(T item)
public T DetachAt(int index)

where both methods return the detached list member as a shallow copy, or maybe as a reference (when reference type), instead of just deleting it like Remove()/RemoveAt() do.

Then, in your case, the operation will shrink to

var temp = list.DetachAt(index);
list.Insert(newindex, temp);

This might make the intention more clear.

[huoyaoyuan]

It won't work so. A linear list is not a linked list and elements can't be "detached" separately.

[StellarWolfEntertainment]

I know it's not exactly what you are asking but you could always right it as an extension method [at least until C# adds this if they do]

public static void IndexMove<T>(this List<T> list, int index, int newIndex) {
    T element = list[index];
    list.RemoveAt(index);
    list.Insert(newIndex, element);
}

but I do agree that this is a fairly major concept that is missing from lists in C#