Working with Classes in vb6 with user selected fields - class

Question

I found out how to create the properties of the class, like this:
private m_Name as string
public property get Name() as string
Name = m_Name
end sub
public property let Name(sval as string)
m_name = sval
end sub
The user will create a document and choose some fields (Name, Birthday, Phone....) inside this document, as I can't know exactly which fields will be chosen by the user, I thought create a class would be the best option.
After I create the class like above, how may I make a loop through this class to check which fields has been chosen by the user?
Any better option for my situation, please, let me know...

Answer 1

If I understood you correctly, you want to know which fields (out of a number of existing fields) user used/initialized?
I see several ways to do it:
1) If your variables do not have default values and must have a non-empty/non-zero values, then you can simply check if a variable is empty or zero. If it is, it hasn't been initialized.
If m_name = "" Then MsgBox "Variable is not initialized"
2) for each field you have, create a boolean fieldName_Initialized so for each field, you would have something like this:
private m_Name as string
private m_name_Initialized as Boolean
public property get Name() as string
Name = m_Name
end sub
public property let Name(sval as string)
m_name = sval
m_name_Initialized = True
end sub
3) you could have a list and add variable names to the list as they become initialized:
Make sure to add Microsoft Scripting Runtime to your References for Dictionary to work.
Dim initialized As Dictionary
Set initialized = New Dictionary
private m_Name as string
private m_name_Initialized as Boolean
public property get Name() as string
Name = m_Name
end sub
public property let Name(sval as string)
m_name = sval
initialized.Add "m_name", True
end sub
Then, to check if the var has been initialized:
If initialized.Exists("m_name") Then
' Var is initialized
4) similar to #3, except use an array of booleans. Tie specific var to a specific index, like m_name is index 0. This way you skip the hassle of controlling variable names (adds to maintenance cause as far as I know you can't get the name of the variable)
Personally, #1 is the most simple, but may not be possible in a certain situations. If #1 does not apply, I would personally pick #2, unless someone can figure out how to get a string representation of a variable name from the variable itself, then #3 is preferred.

Answer 2

I guess what you need is a kind of Nullable-behaviour. Yes you can do this ins VB6 with the datatype Variant. Then you can use the function "IsEmpty()" to check if a property was already set or not.
a little code-example:
Option Explicit
Private m_Vars()
'0 : Name
'1 : Birthday
'2 : Phone
Private Sub Class_Initialize()
ReDim m_Vars(0 To 2)
End Sub
Public Property Get Name() As String
Name = m_Vars(0)
End Property
Public Property Let Name(RHS As String)
m_Vars(0) = RHS
End Property
Public Property Get Birthday() As Date
Birthday = m_Vars(1)
End Property
Public Property Let Birthday(RHS As Date)
m_Vars(1) = RHS
End Property
Public Sub DoSomething()
Dim i As Integer
For i = 0 To UBound(m_Vars)
Dim v: v = m_Vars(i)
If IsEmpty(v) Then
MsgBox "is empty"
Else
MsgBox v
End If
Next
End Sub

Answer 3

If I understand correctly, the user will add tags or something to something like a document (e.g. [Name]) and you want to know how to map your class members to these tags. To do this, you dont really want to loop thru the class members, but the document tags to find out what is needed. When you find a "tag", submit it to your class to fill in the blank.
Part 1 is a parser to find the tags...my VB6 is very rusty, so pseudocode for this:
Const TagStart = "[" ' "$[" is better as it is not likely to appear
Const TagStop = "]" ' "]$" " " "
' make this a loop looking for tags
i = Instr(docScript, TagStart)
j = Instr(docScript, TagStop)
thisTag = Mid(docScript, TagStart, TagEnd )
' not correct, but the idea is to get the text WITH the Start and Stop markers
' like [Name] or [Address]
' get the translation...see below
docText = MyClass.Vocab(thisTag)
' put it back
Mid(docScript, TagStart, TagEnd) = docText
It is actually better to look for each possible legal tag (ie Instr(docScript, "[Name]")) which are stored in an array but you may have to do that in 2 loops to allow that a given tag could be requested more than once.
Part 2 supply the replacement text from MyClass:
Friend Function Vocab(tag as string) As String
Dim Ret as string
Select Case tag
Case "$[NAME]$"
ret = "Name: " & m_Name
' if the caption is part of the "script" then just:
'ret = m_Name
Case "$[ADDRESS]$"
ret = "Address: " & m_Addr
' if not found, return the tag so you can add new Vocab items
' or user can fix typos like '[NMAR]'
Case Else
ret = tag
...
End Select
Return Ret
End Function
The parsing routines in Part 1 could also be a method in your class to process the document "script" which calls a private Vocab.
Edit
a fraction of a 'script' might look like this:
Customer's Name:| $[CUST_FNAME]$ $[CUST_LNAME]$ (ignore the pipe (|) it was a table cell marker)
The parser looks thru the string to find "$[", when it does, it isolates the related tag $[CUST_FNAME]$. If you have a large number, the first part (CUST) can be used as a router to send it to the correct class. Next, call the method to get the translation:
newText = Cust.Vocab(thisTag)
Cust Class just looks at the tag and returns "Bob" or whatever and the parsing loop replaces the tag with the data:
Customer's Name:| Bob $[CUST_LNAME]$
Then just continue until all the tags have been replaced.
With "just" 22 vocab items, you could create a dedicated class for it:
Vocab.Translate(tag ...) as string
Case "$[CUST_FNAME]$"
return Cust.FirstName
...or
Are you trying to work out a way to do this via a DOC object from office? The above is more of from the ground up document composition type thing. For office I'd think you just need some sort of collection of replacement text.
HTH

Answer 4

If the user has a form that they do something to create their document, why not use simple checkbox controls, one for each possible field? If you want to use a loop to check for selected fields make the checkboxes a control array and loop though the array. You can assign the field name to the Tag property, then if the checkbox is checked add the field to an array.