I am not sure how to even clearly phrase this question, so here are two more versions of the same question:
- Can a struct/class implement an interface by delegating to its field/property?
- Can I map an interface implemented by a field/property type to its struct/class?
Here is a code example with pseudo-syntax added to hopefully show what I mean:
public class School : IEnumerable<Student>
{
private List<Student> students expose IEnumerable<Student>;
...
}
If this is not currently possible, is it potentially possible? ...or are there some serious issues with this approach? I reckon this could be just syntactic sugar to get rid of boiler plate code which would otherwise be functionally identical. Example:
public class School : IEnumerable<Student>
{
private List<Student> students;
...
public IEnumerator<Student> GetEnumerator() { return students.GetEnumerator(); }
IEnumerator IEnumerable.GetEnumerator() { return GetEnumerator(); }
}
}
This is of course a very contrived and minimal example. The benefits would be greater when composing interfaces designed for it, especially when there are a lot of methods to "map".
UPDATE: I am aware that I provided a terrible example, but I just wanted to use the simplest example possible. The core of the question is not about a specific scenario. Having said that, my example is bad; so, to better help people who like to see a good example accompany a question, here is a slightly better one:
public interface IValidPeriod
{
DateTime ValidFrom { get; }
DateTime ValidTo { get; }
DateTime ValidThrough { get; }
int DaysValid { get; }
}
public class ValidPeriod : IValidPeriod
{
public DateTime ValidFrom { get; private set; }
public DateTime ValidTo { get; private set; }
public DateTime ValidThrough { get { return ValidTo.AddDays(1); } }
public int DaysValid { get { return (ValidTo - ValidFrom).Days; } }
public ValidPeriod(DateTime from, DateTime to)
{
ValidFrom = from;
ValidTo = to;
}
}
public class Agreement : IValidPeriod
{
...
public ValidPeriod ValidPeriod { get; private set; } exposes IValidPeriod;
...
}
public class Contract : IValidPeriod, ICancellable
{
private Agreement agreement exposes IValidPeriod;
...
}
public class Payment : IValidPeriod, ICancellable
{
public DateTime StartDate { get; set; }
private ValidPeriod validPeriod
{
get { return new ValidPeriod(StartDate, DateTime.Max); }
} exposes IValidPeriod;
...
}
public static class SomeUtility
{
public static void CancelIfValidBefore<T>(List<T> items, DateTime date)
where T : IValidPeriod, ICancellable
{
...
}
}
