Using Enum

[AlexanderBB]

I have a list of strings and numbers that go with them.

I'm sending the string to a Function to return the Number and
was using Select Case but have an idea there's something better.
I tried Enum. Can I use the variable name though, or must be a literal ?

 

[Rick Rothstein]

I have a list of strings and numbers that go with them.

I'm sending the string to a Function to return the Number and
was using Select Case but have an idea there's something better.
I tried Enum. Can I use the variable name though, or must be a literal ?

It must be a literal as it will be handled before the code is compiled. I am pretty sure VB treats Enum's as a special kind of Const statement (everywhere the literal is found, VB replaces it with the equivalent value, and then proceeds to compile the code).

 

[AlexanderBB]

Not quite with you mean Rick, say I have

Enum AccessCol
    Composer = 13
End Enum

Sub TheNum()
Dim MyString As String
MyString = "Composer"

Debug.Print AccessCol.Composer  ' this works

13

'But what if I want to use "myString" variable e.g.
Debug.Print AccessCol.MyString
End Sub

I can't do it, can I ?

 

[Rick Rothstein]

Not quite with you mean Rick, say I have

Enum AccessCol
    Composer = 13
End Enum

Sub TheNum()
Dim MyString As String
MyString = "Composer"

Debug.Print AccessCol.Composer  ' this works

13

'But what if I want to use "myString" variable e.g.
Debug.Print AccessCol.MyString
End Sub

I can't do it, can I ?

No, you cannot do that... Composer must be a literal. If you have ever worked with constants (Const statements), Enum is just a way to bundle several Const statements (without the Const keyword) into a named group. Const statements, and hence Enum members, are evaluated before the code is compiled. What that means (for the code you posted) is that VB will look for AccessCol.Composer in your source code and replace it with the number 13, then it will compile the code. This means the keyword Composer will not be found anywhere within the source code at the time the source code is compiled. Variables that you Dim are only "created" (a memory location is assign to them) during the compile process, hence, a variable cannot be used to set up a reference to an Enum member because by the time the variable is created, the Enum has already been handled and is no longer in existences (only the replaced values are in the source code at that time).

 

[AlexanderBB]

Thanks Rick, I understand now, and prob should stick with the Select Case structure. It works fine, but I wanted to try some alternatives.

 

[Kyle123]

Using a collection is likely the most efficient, with the number as the item and the name as the key

 

[AlexanderBB]

That's a thought too. Thanks.. will try it.