Question

Let say I have 2 lists

public List<TypeA> TypeARecords {get; set;}
public List<TypeB> TypeBRecords {get; set;}

Both TypeA and TypeB implements same Interface (let say IBaseRecord)

Now I have a read only property that returns list of all records

public List<IBaseRecord> AllRecords
{
    get 
    {
        var allRecs = new List<IBaseRecord>();

        foreach ( var rec in TypeARecords)
            allRecs.Add(rec);

        foreach ( var rec in TypeBRecords)
            allRecs.Add(rec);

        return allRecs;
    }
}

This works but I am sure there is more effective or just smarter way to do same thing
Any ideas?

Answer 1

You can make an iterator that returns the items in the list:

public IEnumerable<IBaseRecord> GetAllRecords {
  foreach (var rec in TypeARecords) {
    yield return rec;
  }
  foreach (var rec in TypeBRecords) {
    yield return rec;
  }
}

This way you don’t have to create a new list with all the items, it will just read from the existing lists.

Edit:
As Stan R. suggested, you can use the ToList method to create a copy of the list:

List<IBaseRecord> work = obj.GetAllRecords().ToList();

This is a bit better than having a property that returns a new list, as the ownership of the list gets clearer. Also, a property should not do such heavy lifting as creating lists, at least not every time the property is read.