GetNameFromDispID, ShowPropertyPageEditor

Look up a member’s name from its dispatch ID, and show the property page that edits one property of an object.

Both procedures are declared Hidden and Restricted, so IntelliSense lists leave them out. They exist for twinBASIC’s own packages, which call them while hosting property pages; ordinary code does not need them.

GetNameFromDispID

Returns the name of the member of an object that has a given dispatch ID.

Syntax: GetNameFromDispID( Object, DispID ) As String

Object: required An object that exposes type information. An IUnknown parameter, so any object reference is accepted.
DispID: required Long. The dispatch ID (DISPID) of a member of Object.

The name comes from the object’s type information. GetNameFromDispID(x, 0) is the name of the default member and -4 that of the enumerator member, when the object has them.

Dim Table As Object = CreateObject("Scripting.Dictionary")
Debug.Print GetNameFromDispID(Table, 0)     ' Item
Debug.Print GetNameFromDispID(Table, 2)     ' Count
Debug.Print GetNameFromDispID(Table, -4)    ' _NewEnum

The call raises an error when no name can be returned; Common Errors lists them. For an object of a class that twinBASIC compiles, a DispID that is no member’s raises error 5, Invalid procedure call or argument, and -4 raises -2147319765, Element not found., when the class has no enumerator member.

The VB package’s PropertyPage calls it when the property sheet asks a page to edit a property by dispatch ID, to find the property’s name.

ShowPropertyPageEditor

Shows the property page that edits one property of a control.

Syntax: ShowPropertyPageEditor Caption, Object, DispID

Caption: required String. The title of the page.
Object: required An IUnknown reference to the control whose property is edited.
DispID: required Long. The dispatch ID of the property to edit.

The VB package’s ActiveX control host calls it with the control’s name, the control’s object and the property’s dispatch ID, when it is asked to edit a property that is linked to a property page. The call that shows all of a control’s property pages at once is the hidden ShowPropertyPages.

Sub EditProperty(ByVal Control As Object, ByVal PropertyDispId As Long)
    ShowPropertyPageEditor "Properties", Control, PropertyDispId
End Sub

Common Errors

Error	When
-2147467261 (`&H80004003`), Invalid pointer	Object is Nothing
-2147467263 (`&H80004001`), Not implemented	GetNameFromDispID is given an object that has no type information, such as a Collection
-2147467262 (`&H80004002`), No such interface supported	GetNameFromDispID is given an object that does not support IDispatch, such as a TbExpressionService ShowPropertyPageEditor is given an object that has no property pages
-2147319765 (`&H8002802B`), Element not found.	GetNameFromDispID is given an object described by a type library, such as a Scripting.Dictionary, and a DispID that is no member’s
94 (`&H5E`), Invalid use of Null	Caption or DispID is Null
424 (`&H1A8`), Object required	Object is Null

GetNameFromDispID, ShowPropertyPageEditor