VTODO - separate status and completed properties

[maknapp]

Setting the Todo.Status property to "COMPLETED" sets the Todo.Completed property to NOW as well. Both of these properties are optional and should be able to be set independently.

This behavior should be in a separate method that clearly states it will set both properties.

Todo.MarkAsCompleted(Instant? completed = null);

[axunonb]

Fully agree. To my understanding of RFC 5545:

• STATUS is optional
• COMPLETED is optional
• When STATUS:COMPLETED is used, the COMPLETED property SHOULD (not MUST) be specified

So properties should be independently settable.

I'm also not sure whether IsActive() and IsCompleted() make sense. They evaluate previous periods, while I think each VTODO instance should be considered individually.

An attempt to determine: "Was a previous instance of this recurring TODO completed, and does that affect whether the current instance is completed?" in quite unusual, isn't it?

A simple implementation like

public bool IsCompleted() => Status == TodoStatus.Completed;
public bool IsActive() => Status != TodoStatus.Completed && Status != TodoStatus.Cancelled;

should be enough.