Manager/Container class vs static class methods
- by Ben
Suppose I a have a Widget class that is part of a framework used independently by many applications. I create Widget instances in many situations and their lifetimes vary. In addition to Widget's instance specified methods, I would like to be able to perform the follow class wide operations:
Find a single Widget instance based on a unique id
Iterate over the list of all Widgets
Remove a widget from the set of all widgets
In order support these operations, I have been considering two approaches:
Container class - Create some container or manager class, WidgetContainer, which holds a list of all Widget instances, support iteration and provides methods for Widget addition, removal and lookup. For example in C#:
public class WidgetContainer : IEnumerable<Widget
{
public void AddWidget(Widget);
public Widget GetWidget(WidgetId id);
public void RemoveWidget(WidgetId id);
}
Static class methods - Add static class methods to Widget. For example:
public class Widget
{
public Widget(WidgetId id);
public static Widget GetWidget(WidgetId id);
public static void RemoveWidget(WidgetId id);
public static IEnumerable<Widget AllWidgets();
}
Using a container class has the added problem of how to access the container class. Make it a singleton?..yuck! Create some World object that provides access to all such container classes?
I have seen many frameworks that use the container class approach, so what is the general consensus?
