A wish for enumerated strings

slaycock · #1 07-19-2017, 05:47 AM

I know these can't be done in VBA but in my current project I have a number of cases where a string based enumeration would save a lot of sideways coding.

So this is really a question of how do you program around such a restriction.

macropod · #2 07-19-2017, 03:25 PM

What do you mean by 'string based enumeration' and 'sideways coding'? What are you trying to achieve?

slaycock · #3 07-20-2017, 01:23 AM

I'm just noticing that there are a number of items which use strings labels where the 'elegance' of the code might be improved by enumertion based on string rather than Longs

Such items include

• Custom Document Properties
• Custom XML Parts
• CustomUI Ribbon Control Identifiers
• Collections/Scripting Dictionaries
• User types that need string labels (e.g. user defined styles.

For example I have a set of names for elements in a CustomXML part. There are many sets of these elements.

Code:

Enum XMLTags

  TagName1 = "Name1"
  TagName2 = "Name2"
  TagName3 = "Name3"
....
  TagName25

End enum


For myTag = TagName1 to TagName13

  <Code for each tag>

Next

Rather than

defining the TagNames as Constants, Adding the Constant to an Array, defining an enumeration to index the TagNames in the array and then

Code:

Enumeration for tag index
Array for tag names
Assgning values to the name array
 
then

For myTagIndex = TagNameArray(enTagName1) to TagNameArray(enTageName13)

<code relating to tag>
Next

Or constructing the tag name on the run

Code:

Const  TagBase as string="Name"
Dim myTag as String
Dim myTagIndex as Long

For myTagIndex=1 to 13
  
  myTag = TagBase & myTabIndex
 if Dictionary(Key:=myTag).objectitem=<a value> then

end if

Next

None of the above cause me problems, but they do add an amount of coding 'cruft' that could be avoided with enumerated strings.

Now I hold my hands up and admit that I'm self taught with the aid of this forum, VBA in a Nutshell book, the sometimes useful MS help pages and other random reading via Google so it may be that I'm missing something very obvious.

In a nutshell I'm not stuck, just wondering about the best way to improve the readability of my code.

macropod · #4 07-20-2017, 04:31 PM

You could just add the items to an array directly:

Code:

Sub Demo()
Dim i As Long, myArray()
myArray = Array("Name1", "Name2", "Name3", "Name4", "Name5", "Name6", "Name7", "Name8")
For i = LBound(myArray) To UBound(myArray)
  MsgBox myArray(i)
Next
End Sub

If need be, such an array can even be constructed on the fly.

slaycock · #5 07-21-2017, 08:11 AM

The array approach was one of my first solutions (except I was using split with a single string). But to make the code more meaningful I also defined an enumeration to index the array.

This allowed me to say things like

docXMLProp(<propertyname>)

Which still leaves what should be a constant writable. So I made the array behave like a constant by putting it in a class. That leaves me with the choice of one get statement per enumeration value

docXMLProp.<propertyname>

or a single get property with a case statement to allow the form

docXMLProp.item(<propertyname>) or
docXMLProp(<propertyname>)

if you go through the rigamarole of exposting the class, setting the default property as item then reimporting.

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