The System.Windows.Forms.BindingSource class uniformly handles different data sources. Ideally the BindingSource.List property should be set to a general IList. However, sometimes it may be necessary to cast this property to a more specific type. The following table shows the underlying list type, which depends on the type or value of the data source.

BindingSource.DataSource and BindingSource.DataMember are null	An empty ArrayList.
BindingSource.DataSource is null, but BindingSource.DataMember is not null	None; an attempt to get the BindingSource.List will throw an ArgumentException.
An Array instance	An Array.
An System.ComponentModel.IListSource instance	The return value from a call to the System.ComponentModel.IListSource.GetList method of this System.ComponentModel.IListSource instance.
An System.ComponentModel.IBindingList instance	An System.ComponentModel.IBindingList.
An IList instance	An IList.
A non-IList instance of type "T"	A System.ComponentModel.BindingList`1 with one element.
An System.ComponentModel.ICustomTypeDescriptor instance	An ArrayList with one element.
An IEnumerable	An ArrayList with the elements copied over.
The Array type with BindingSource.DataMember of item type "T"	A System.ComponentModel.BindingList`1.
A Type that represents an System.ComponentModel.IListSource or System.ComponentModel.ITypedList	An instance created by a call to the Activator.CreateInstance(Type) method of the Activator class. A NotSupportedException may be thrown.
The IList type with BindingSource.DataMember of item type "T" -or- A non-IList type	A System.ComponentModel.BindingList`1.
The System.ComponentModel.ICustomTypeDescriptor type	None; an attempt to get the BindingSource.List will throw an NotSupportedException.

If the type retrieved is the IList interface, the underlying collection may be more complex, such as an ArrayList or System.Data.DataView class.

Namespace: System.Windows.Forms
Assembly: System.Windows.Forms (in System.Windows.Forms.dll)
Assembly Versions: 2.0.0.0