ActivityCollection.IEnumerable(Of Activity).GetEnumerator Method
Returns an enumerator that iterates through the collection.
Assembly: System.Workflow.ComponentModel (in System.Workflow.ComponentModel.dll)
'Declaration Private Function GetEnumerator As IEnumerator(Of Activity) Implements IEnumerable(Of Activity).GetEnumerator
Return ValueType: System.Collections.Generic.IEnumerator(Of Activity)
An IEnumerator(Of T) that can be used to iterate through the collection.
The foreach statement of the C# language (for each in C++, For Each in Visual Basic) hides the complexity of the enumerators. Therefore, using foreach is recommended, instead of directly manipulating the enumerator.
Enumerators can be used to read the data in the collection, but they cannot be used to modify the underlying collection.
Initially, the enumerator is positioned before the first element in the collection. At this position, Current is undefined. Therefore, you must call MoveNext to advance the enumerator to the first element of the collection before reading the value of Current.
If MoveNext passes the end of the collection, the enumerator is positioned after the last element in the collection and MoveNext returns false. When the enumerator is at this position, subsequent calls to MoveNext also return false. If the last call to MoveNext returned false, Current is undefined. You cannot set Current to the first element of the collection again; you must create a new enumerator instance instead.
An enumerator remains valid as long as the collection remains unchanged. If changes are made to the collection, such as adding, modifying, or deleting elements, the enumerator is irrecoverably invalidated and its behavior is undefined.
The enumerator does not have exclusive access to the collection; therefore, enumerating through a collection is intrinsically not a thread-safe procedure. To guarantee thread safety during enumeration, you can lock the collection during the entire enumeration. To allow the collection to be accessed by multiple threads for reading and writing, you must implement your own synchronization.
Default implementations of collections in the System.Collections.Generic namespace are not synchronized.
- Full trust for the immediate caller. This member cannot be used by partially trusted code. For more information, see Using Libraries from Partially Trusted Code.