[RESOLVED] Test if argument is part of enumaration

[Dnereb]

The question is straight forward how can I test is an argument passed down a function is part of an enummeration in one statment.

Example enumeration:

Public Enum EnumBaseKeys
HKEY_CLASSES_ROOT = &H80000000
HKEY_CURRENT_USER = &H80000001
HKEY_LOCAL_MACHINE = &H80000002
HKEY_USERS = &H80000003
End Enum

Example Function:

Public Function Makekey(Optional Hkey As EnumBaseKeys, Optional Subkey As String) As Boolean

now how to check if Hkey is a member of EnumBasekeys?

Thanks in advance.

[EricDV]

Public Function Makekey(Optional Hkey As EnumBaseKeys, Optional Subkey As String) As Boolean
    If Hkey = HKEY_CLASSES_ROOT _
        Or Hkey = HKEY_CURRENT_USER _
        Or Hkey = HKEY_LOCAL_MACHINE _
        Or Hkey = HKEY_USERS Then
        'it is a member
 
    Else
        'it is not a member
    End If
End Function

[Comintern]

I don't think there is any easy way to do this. From a functional standpoint, all an enum does is create a list of constants with a namespace. Your enum would be identical to this as far as the compiler was concerned:

Const HKEY_CLASSES_ROOT = &H80000000
Const HKEY_CURRENT_USER = &H80000001
Const HKEY_LOCAL_MACHINE = &H80000002
Const HKEY_USERS = &H80000003

[Dnereb]

Public Function Makekey(Optional Hkey As EnumBaseKeys, Optional Subkey As String) As Boolean
    If Hkey = HKEY_CLASSES_ROOT _
        Or Hkey = HKEY_CURRENT_USER _
        Or Hkey = HKEY_LOCAL_MACHINE _
        Or Hkey = HKEY_USERS Then
        'it is a member
 
    Else
        'it is not a member
    End If
End Function

Thanks to both of you, I hoped there was an way to compare to them all at once. but that seems to be wishfull thinking.

Thanks for taking the time to reply.

[penagate]

Thanks to both of you, I hoped there was an way to compare to them all at once. but that seems to be wishfull thinking.

Sure there is!

Public Enum EnumBaseKeys
    [_ENUMBASEKEYS_FIRST] = &H80000000
    HKEY_CLASSES_ROOT = &H80000000
    HKEY_CURRENT_USER = &H80000001
    HKEY_LOCAL_MACHINE = &H80000002
    HKEY_USERS = &H80000003
    [_ENUMBASEKEYS_LAST] = &H80000003
End Enum
 
' .......
 
Public Function Makekey(Optional Hkey As EnumBaseKeys, Optional Subkey As String) As Boolean
    If ((Hkey >= [_ENUMBASEKEYS_FIRST]) And (Hkey <= [_ENUMBASEKEYS_LAST]) Then
        ' ...
    End If
End Function

The brackets around the FIRST and LAST members hide them from the Intellisense menu, so you won't accidentally use them when assigning values

[Dnereb]

Thanks Penagate!

Your Briljant!
Saves me a lot of trouble, not on this enumaration only but on several others I plan to use.

As you've might have guessed is this just for a registerclass. But I find it very usefull to use enums for arguments in classes.

If you don't mind I'll copy your answer (with a reference) to another forum
that gave the same "No can do" as a result.

Thanks.

[penagate]

No problems, spread the knowledge!

[Dnereb]

If you like to look at it....
Copy of penagate's reply

[Joacim Andersson]

I must have missed something here because I honestly don't see the advantage of adding two hidden enumeration values. Since the values follow each other why not simply use HKEY_CLASSES_ROOT and HKEY_USERS instead of the two hidden values? It might be a nice trick to be able to do so, but I really can't see the advantage... please enlighten me.

[penagate]

Well, the advantage is that it makes it clear which is the first and last, if you need to add any more enumeration members you don't have to hunt through the code to change the constants used, simply update the values of the _FIRST and _LAST members.

[Dnereb]

It is as penagate said but the enumeration doesn't have to be continues either:
This special sequence works fine as well.

Public Enum EnumBaseKeys
    [_DOCTYPES_FIRST] = 0
    ALL = 0
    ACCESS = 1
    EXCEL = 2
    WORD = 4
    POWERPOINT = 8
    ACAD_DWG = 16
    ACAD_DXF = 32
    EXCLUDE = 64
    [_DOCTYPES_LAST] = 127     '(64 * 2) - 1
End Enum

Although the example is a bit silly you coud still test for last and first because all the numbers in the gaps are a combination of two or more enummerations keys (To filter them you could use bitwise comparison).

[Joacim Andersson]

Well that would of course depend on if a setting can be a combination of different values or not. I can buy the argument that it would be easier to add new enumeration values even though I still think it is a bit of an overkill to do so with an enumeration of the HKEY's available in the registry. Future versions of Windows might have new root keys but I doubt it.

[Dnereb]

I don't see why it's overkill a enummeration doesn't gulp memory as far as I know
it's just a bit more typing now
(Class development) to avoid typing and mistyping later.

About the register...well take enough time and I'm almost sure it will be extended.
in the future, but I doubt my code will survive that long.