I am attempting to write a SortableBindingList that I can use for my application. I have found lots of discussion about how to implement basic sorting support so that the BindingList will sort when used in the context of a DataGridView or some other bound control including this post from StackOverflow:
DataGridView sort and e.g. BindingList<T> in .NET
This is all very helpful and I have implemented the code, tested, etc. and it's all working, but in my particular situation, I need to be able to support a simple call to Sort() and have that call use the default IComparable.CompareTo() to do the sorting, rather than making a call to ApplySortCore(PropertyDescriptor, ListSortDirection).
The reason is because I have quite a great deal of code that's depending on the Sort() call because this particular class originally inherited from List and was recently changed to be a BindingList.
So specifically, I have a class called VariableCode and a collection class called VariableCodeList. VariableCode implements IComparable and the logic in there is moderately complex based on several properties, etc...
public class VariableCode : ... IComparable ...
{
public int CompareTo(object p_Target)
{
int output = 0;
//some interesting stuff here
return output;
}
}
public class VariableCodeList : SortableBindingList<VariableCode>
{
public void Sort()
{
//This is where I need help
// How do I sort this list using the IComparable
// logic from the class above?
}
}
I've made a few failed attempts at repurposing the ApplySortCore method in the Sort(), but what keeps thwarting me is that the ApplySortCore expects a PropertyDescriptor to do its sort and I can't figure out how to get that to use the IComparable.CompareTo() logic.
Can someone point me in the right direction?
Many thanks.
EDIT: This is the final code based on Marc's response for future reference.
/// <summary>
/// Sorts using the default IComparer of T
/// </summary>
public void Sort()
{
sort(null, null);
}
public void Sort(IComparer<T> p_Comparer)
{
sort(p_Comparer, null);
}
public void Sort(Comparison<T> p_Comparison)
{
sort(null, p_Comparison);
}
private void sort(IComparer<T> p_Comparer, Comparison<T> p_Comparison)
{
m_SortProperty = null;
m_SortDirection = ListSortDirection.Ascending;
//Extract items and sort separately
List<T> sortList = new List<T>();
this.ForEach(item => sortList.Add(item));//Extension method for this call
if (p_Comparison == null)
{
sortList.Sort(p_Comparer);
}//if
else
{
sortList.Sort(p_Comparison);
}//else
//Disable notifications, rebuild, and re-enable notifications
bool oldRaise = RaiseListChangedEvents;
RaiseListChangedEvents = false;
try
{
ClearItems();
sortList.ForEach(item => this.Add(item));
}
finally
{
RaiseListChangedEvents = oldRaise;
ResetBindings();
}
}
Emulating a property just to do the sort is probably overkill.
The first thing to look at is Comparer<T>.Default
. It might, however, turn out that the easiest thing to do is to:
List<T>
or similarbtw, you should be disabling notifications during your existing sort, too.
public void Sort() {
// TODO: clear your "sort" variables (prop/order)
T[] arr = new T[Count];
CopyTo(arr, 0);
Array.Sort(arr);
bool oldRaise = RaiseListChangedEvents;
RaiseListChangedEvents = false; // <=== oops, added!
try {
ClearItems();
foreach (T item in arr) {
Add(item);
}
} finally {
RaiseListChangedEvents = oldRaise;
ResetBindings();
}
}