Using Enum in an interface

[UrinatinventuM]

Hi ppl,

I want to use enumerations in an ActiveX DLL. This ActiveX DLL uses interfaces. I want to use those enumerations in properties, so the user is restricted from certain values. For example, now I have a property to which I assign an integer, but I have a check inside the property which checks if the input is 0,1,2 or 3. If not, the property raises an error. This is very difficult especially when another developer wants to use my DLL, because he has to read about 2000 lines in which all the valid inputs are given (and trust me, there are a LOT !)

Could anybody please help me with this?!?

[jim mcnamara]

Public Enum IColors
   icMistyRose = &HE1E4FF&
   icSlateGray = &H908070&
   icDodgerBlue = &HFF901E&
   icDeepSkyBlue = &HFFBF00&
   icSpringGreen = &H7FFF00&
   icForestGreen = &H228B22&
   icGoldenrod = &H20A5DA&
   icFirebrick = &H2222B2&
End Enum

Property Let Color(Ic as IColors)

End Property

This uses an enum as a property, limits the entries to the items enumerated { icMistRose ... icFireBrick}, and will show up in the type libaray (& object browser).

That what you need?

[UrinatinventuM]

I've already tried some implementations of an enum in an interface, but it doesn't seem to work in ActiveX DLL's. On the other hand, it does work work with ActiveX EXE's! But I don't want to use A' EXE's!

Greetz,

Bartozz

[jim mcnamara]

Please show me how you define the interface, then show me an implementation.

[UrinatinventuM]

Here is some implementation (it's an ActiveX DLL):

iClass
-------
Option Explicit

Property Get Interface() As String
End Property

' Filename.
Property Let FileName (nv As String)
End Property

Property Get FileName () As String
End Property

' Name.
Property Let Option (nv As Integer)
End Property

Property Get Option () As Integer
End Property
.
.
.

cClass
--------
Option Explicit

Implements iClass

Private msFileName$
Private miOption%

Property Get iClass_Interface() As String
iClass_Interface = "iClass"
End Property

Private Property Let iClass_FileName(nv As String)
msFileName = nv
End Property

Private Property Get iClass_FileName() As String
iClassFileName = msFileName
End Property

Property Let iClass_Option (nv As Integer)
Select Case nv
Case 0, 1, 2, 3
miOption = nv
Case Else
Err.Raise c__INVALID_VALUE, iClass_Interface, c__INVALID_VALUE_TEXT
End Select
End Property

Property Get iClass_Option () As Integer
iClass_Option = miOption
End Property
.
.
.

Now it's about the Option-thing... The Option property has only 4 options, as shown: 0, 1, 2 and 3. Now I do it with the Select Case thingie, but it has to be arranged with Enumerations! Not only the possible values will be shown explicitly to the developer using my component, so he/she doesn't have to read stacks of paper to figure out which values can be used!

Do you get my idea?

[jim mcnamara]

This DOES work in an ActiveX dll...

In the interface definition you have to use the enumeration

' Name.
Property Let Option (nv As enumMyclass)
End Property

Property Get Option () As enumMyClass
End Property
.
.
In the implementation - (another .cls module)

Public enum enumMyClass
enumMyClassRed = 1
enumMyCLassGreen = 2
End enum

Private mMyClass as enumMyClass


Property Let iClass_Option (nv As enumMyCLass)
' you don't need a case statement because you'll always
' get the right range of values
mMyCLass = nv
End Property

Property Get iClass_Option () As enumMyClass
iClass_Option = mMyCLass
End Property

[Abu haider]

Remember, however, though enumeration suggests a list of possible values, it doesn't restrict the user/developer from assigning values which are not in the Enum List. Consider the following:

Enum Bang
    BangOne
    BangTwo
End Enum

A property of type Bang will cause VB to suggest BangOne and BangTwo as the possible values which correspond to 0 and 1, however, it is possible to assign values other than these two to the property and VB will not perform any Validation checking, nor it will restrict from any other numeric value.

Enums perfectly work with all type of projects.