Why is this an issue?
When Select Case statements have large sets of case clauses, it is usually an attempt to map two sets of data. A
Dictionary should be used instead to make the code more readable and maintainable.
Noncompliant code example
With a "Maximum number of case" set to 4
Public Class TooManyCase
Public Function SelectCase(Ch As Char) As Integer
Select Case Ch
Case "a"c
Return 1
Case "b"c, "c"c
Return 2
Case "d"c
Return 3
Case "e"c
Return 4
Case "f"c, "g"c, "h"c
Return 5
Case Else
Return 6
End Select
End Function
End Class
Compliant solution
Public Class TooManyCase
Private fMatching As New Dictionary(Of Char, Integer) From {
{"a"c, 1}, {"b"c, 2}, {"c"c, 2}, {"d"c, 3},
{"e"c, 4}, {"f"c, 5}, {"g"c, 5}, {"h"c, 5},
}
Public Function SelectCase(Ch As Char) As Integer
Dim Value As Integer
If fMatching.TryGetValue(Ch, Value) Then
Return Value
Else
Return 6
End If
End Function
End Class
Exceptions
This rule ignores Select Cases over Enums and empty, fall-through cases.
