Error handling of multiple class attributes - excel

Question

I have a class that holds data in separate attributes (I chose this design instead of an array or scripting.dictionary because I will be using these data for the construction of a decision tree and I want to make use of IntelliType while I construct it.).
The data are loaded from an excel spreadsheet in the form of floats, so I am storing them in a long datatype, but from time to time it happens so that a value is missing and is replaced by an "NA" string.
I would like to create an error-handling routine, that, if a non-numeric value is encountered, would replace the content with a value -1.
I know I could do this with checking with IsNumeric() or error-handling, but I don't know how to make it work for every one of the many attributes the class holds and I don't really like the solution to write a specific error-handling code for every one of them (storing each of them in a separate attribute is not elegant as well, but I find this a price I am willing to pay for the advantage of shorter syntax in the decision tree).
Is there a way to pass a value to a variable, that just encountered a type-mismatch error, by the error-handling code independent of the variable name?
A simple example with several of the attributes:
Option Explicit
Dim B_LYM As Long
Dim B_mem As Long
Dim B_CXCR3 As Long
Dim B_CXCR4_MFI As Long
Public Sub SetData(data as Range)
On Error Goto err_handler
B_LYM = data.Cells(1, 1)
B_mem = data.Cells(1, 2)
B_CXCR3 = data.Cells(1, 3)
B_CXCR4_MFI = data.Cells(1, 4)
err_handler:
'I need something like this:
'if valuebeingstored = "NA" then targetvariable = -1
End Sub
It could be that some other approach could be better and I am gladly open to options, I only want to emphasize that I would really like make use of IntelliType when constructing the decision tree. I was considering using scripting.dictionary, but the syntax will bloat the code very quickly.

Answer 1

You said you have a Class and therefore could include the function to check the input and return -1 inside the class and use the Get and Let properties to call the function.
Here is an example class (named clsDataStuff) demonstrating this:
Option Explicit
Private c_B_LYM As Double
Private c_B_mem As Double
Private c_B_CXCR3 As Double
Private c_B_CXCR4_MFI As Double
Public Property Let B_LYM(varValue As Variant)
c_B_LYM = ParseDouble(varValue)
End Property
Public Property Get B_LYM()
B_LYM = c_B_LYM
End Property
Public Property Let B_mem(varValue As Variant)
c_B_mem = ParseDouble(varValue)
End Property
Public Property Get B_mem()
B_mem = c_B_mem
End Property
Public Property Let B_CXCR3(varValue As Variant)
c_B_CXCR3 = ParseDouble(varValue)
End Property
Public Property Get B_CXCR3()
B_CXCR3 = c_B_CXCR3
End Property
Public Property Let B_CXCR4_MFI(varValue As Variant)
c_B_CXCR4_MFI = ParseDouble(varValue)
End Property
Public Property Get B_CXCR4_MFI()
B_CXCR4_MFI = c_B_CXCR4_MFI
End Property
Private Function ParseDouble(varValue As Variant) As Double
If IsNumeric(varValue) Then
ParseDouble = CDbl(varValue)
Else
ParseDouble = -1
End If
End Function
Noting that:
the Let property expects a Variant because you say your input could be a number, or a string
the Get property returns Double as you said your inputs are floats so Double is better than Long
the ParseDouble function simply checks for a numeric input and returns -1 otherwise
Then, in your module code:
Option Explicit
Dim B_LYM As Long
Dim B_mem As Long
Dim B_CXCR3 As Long
Dim B_CXCR4_MFI As Long
Public Sub Test()
Dim objDataStuff As clsDataStuff
Set objDataStuff = New clsDataStuff
objDataStuff.B_LYM = 1 'data.Cells(1, 1)
objDataStuff.B_mem = 2 'data.Cells(1, 2)
objDataStuff.B_CXCR3 = "a" 'data.Cells(1, 3)
objDataStuff.B_CXCR4_MFI = True 'data.Cells(1, 4)
Debug.Print objDataStuff.B_LYM
Debug.Print objDataStuff.B_mem
Debug.Print objDataStuff.B_CXCR3
Debug.Print objDataStuff.B_CXCR4_MFI
End Sub
Returns an output of:
1
2
-1
-1
Intellisense is available and you get validation of the input:
Edit - regarding the comment on dynamically setting a target variable.
Your class can be:
Option Explicit
Public B_LYM As Double
Public B_mem As Double
Public B_CXCR3 As Double
Public B_CXCR4_MFI As Double
Public Sub SetVar(ByVal strVarName As String, ByVal varValue As Variant)
Dim dblValue As Double
Dim strToEval As String
If Not MemberExists(strVarName) Then Exit Sub
dblValue = ParseDouble(varValue) ' do the parse
CallByName Me, strVarName, VbLet, dblValue ' dynamically assign the value
End Sub
Private Function ParseDouble(varValue As Variant) As Double
If IsNumeric(varValue) Then
ParseDouble = CDbl(varValue)
Else
ParseDouble = -1
End If
End Function
Private Function MemberExists(strVarName) As Boolean
Dim blnTest As Boolean
Dim varValue As Variant
On Error GoTo ErrHandler
varValue = CallByName(Me, strVarName, VbGet)
blnTest = True
GoTo ExitFunction
ErrHandler:
blnTest = False
ExitFunction:
MemberExists = blnTest
End Function
Where:
All the variables are Public and you still get Intellisense but avoid all the repetitive Let and Get code
A single SetVar method uses CallByName to dynamically set a target variable
Two problems:
You need the clunky MemberExists function to prevent SetVar trying to assign a value to a member that does not exist - otherwise this generates an error (438) but perhaps this is something you need in your logic ?
You can still assign values to the target variable with e.g. objDataStuff.B_CXR3 = "foo" which alsos produces an error for anything other than a number.
The example code shows the problem below. But sticking with SetVar method will produce the same output as above.
Option Explicit
Dim B_LYM As Long
Dim B_mem As Long
Dim B_CXCR3 As Long
Dim B_CXCR4_MFI As Long
Public Sub Test()
Dim objDataStuff As clsDataStuff
Set objDataStuff = New clsDataStuff
objDataStuff.SetVar "B_LYM", 1
objDataStuff.SetVar "B_mem", 2
objDataStuff.SetVar "B_CXCR3", -1
objDataStuff.SetVar "B_CXCR4_MFI", True
objDataStuff.SetVar "foobar", 999
' working around SetVar here generates an error
objDataStuff.B_CXCR3 = "bad"
Debug.Print objDataStuff.B_LYM
Debug.Print objDataStuff.B_mem
Debug.Print objDataStuff.B_CXCR3
Debug.Print objDataStuff.B_CXCR4_MFI
End Sub