You design a C# indexer using an attribute with the <<Indexer>> stereotype. Another attribute with the <<IndexerImplementation>> stereotype is automatically created, it is displayed with an underscore sign in the list of attributes. The corresponding getter and setter operations are also automatically created.
You can get rid of the implementation attribute.
If you remove both getter and setter operations, the attribute no longer has the <<Indexer>> stereotype.
When you define a <<Indexer>> attribute, the attribute changeability and the getter/setter operations are tightly related as explained in the following table:
|
Operations |
Indexer attribute changeability |
|---|---|
|
If you keep both getter and setter operations |
Indexer is Changeable |
|
If you remove the setter operation of a changeable property |
Indexer becomes Read-only |
|
If you remove the getter operation of a changeable property |
Indexer becomes Write-only |
On the other hand, if you modify the indexer changeability, operations will reflect this change, for example, if you turn a changeable indexer into a read-only indexer, the setter operation is automatically removed.
In the following example, class Person contains indexer attribute Item. The parameter used to sort the property is String Name:.
public class Person
{
private Hashtable _childAges;
// Indexer Item
private int this[String name]
{
get
{
return (int)_ChildAges[name];
}
set
{
_ChildAges[name] = value;
}
}
}
Person someone;
someone ["Alice"] = 3;
someone ["Elvis"] = 5;
The following table lists the different indexer modifiers supported in PowerDesigner:
|
C# property modifier |
PowerDesigner equivalent |
|---|---|
|
New |
New extended attribute set to True |
|
Usafe |
Usafe extended attribute set to True |
|
Virtual |
Virtual extended attribute set to True |
|
Override |
Override extended attribute set to True |
|
Extern |
Extern extended attribute set to True |
|
Abstract |
Abstract extended attribute set to True |
|
Sealed |
Sealed extended attribute set to True |