Script Engine - VB.NET Based

[Joacim Andersson]

Was not about hurting feelings more about manors.

I don't get it? What's been wrong with my manor? I have done nothing but trying to help you in this thread and when I mentioned that I have a hard time following spaghetti code which GOTO's lead to, you took that as an insult. It was not meant as such, I just want you to understand good coding practices.

Over to your code:

If you're still talking about how to avoid Goto statements, then this is one way of doing it:

Private Function CheckForVar(strline As String) As String
    ' Changed the name of all local variables to be
    ' camelCased instead of PascalCased (leading lower case character)
    Dim tmpLine As String = strline
    Dim currentChar As String = ""
    Dim varName As String = ""
    Dim varValue As String = ""
    Dim pos As Integer = 0
    Dim posT As Integer = Len(strline)
    Dim check As Boolean = False
    Dim done As Boolean = False ' <-- I added this

    Do  ' <-- Replaced your Label with a Do loop
        For i = 0 To PosT - 1 ' <-- Change the For loop so it loops from 0. This is for SubString to work correctly
            currentChar = tmpLine.SubString(i, 1) '<-- Changed the MID call to .Net SubString
            If (currentChar = TABLE_VARIABLE_SYNTAX) Then
                If (check = False) Then
                    check = True
                    pos = i + 1 '<--- Added 1 since I changed the loop to be zero based
                Else
                    RaiseError("Unexpected variable symbol")
                    Return ""
                    'Removed the Exit Function since it will never be reached
                End If
            End If
            If (check = True) Then
                If (currentChar = " ") Then
                    varName = Replace(varName, TABLE_VARIABLE_SYNTAX, "")
                    varValue = Variables.GetVar(VarName)
                    tmpLine = RebuildString(tmpLine, varValue, pos, pos + Len(varName))
                    check = False
                    varName = ""
                    varValue = ""
                    done = False '<-- Added this
                    Exit For ' <-- Instead of a GOTO simply Exit the For loop
                End If
                If (i = posT - 1) Then ' <-- Added -1 since For loop is zero based
                    varName = Replace(varName, TABLE_VARIABLE_SYNTAX, "")
                    varValue = Variables.GetVar(varName)
                    tmpLine = RebuildString(tmpLine, varValue, pos, pos + Len(varName))
                    check = False
                    varName = ""
                End If
            End If
    
            If (check = True) Then
                varName = varName & currentChar
            End If
            done = True ' <--- Added this. This will never be set if we exit the For loop
        Next
    Loop Until done '<-- Added this

    Return tmpLine
End Function

I put in comment for the changes I made but the main changes is that the code block is now inside a Do ... Loop Until loop instead of having a label and a GOTO statement.

I also changed your Mid call since that is an older function from VB6, a more ".Net way" of doing it is to call the String.SubString method.

I also changed the casing of all your local variables. It is a de facto standard in .Net to use camelCasing (first character in lower case) for local variables and PascalCase (first character in upper case) for methods, properties, and public fields.

I also removed a Exit Function line since you had a Return statement on the line before it. As soon as you hit a return the sub/function will exit. So the Exit Function was just redundant and you would never reach it.

I couldn't of course test this since I don't have all the necessary code but I hope I haven't introduced any errors.

[TheBarret]

End Function[/code]I put in comment for the changes I made but the main changes is that the code block is now inside a Do ... Loop Until loop instead of having a label and a GOTO statement.

I also changed your Mid call since that is an older function from VB6, a more ".Net way" of doing it is to call the String.SubString method.

I also changed the casing of all your local variables. It is a de facto standard in .Net to use camelCasing (first character in lower case) for local variables and PascalCase (first character in upper case) for methods, properties, and public fields.

I also removed a Exit Function line since you had a Return statement on the line before it. As soon as you hit a return the sub/function will exit. So the Exit Function was just redundant and you would never reach it.

I couldn't of course test this since I don't have all the necessary code but I hope I haven't introduced any errors.

Okay this is indeed the better "other" solution, i appreciate this example, once this is seen i'd never go bad again. Thanks J.

-TB

[SJWhiteley]

The 'Goto is bad' is really a rule. Generally, the use of goto implies a programmer with limited experience, is unwilling to listen, is simply resting on their laurels, or all of the above.

Here's an example of using GOTO statements on a common algorithm:

Public Sub DoSomething()
    Dim a() As Long = New Long() {6, 9, 2, 8, 1, 12, 5, 4, 0, 3, 2, 6, 4}
    Call DoSomething(a)
    Dim i As Integer = 0
12:
    Debug.WriteLine(a(i))
    i = i + 1
    If i < a.Length Then GoTo 12
  End Sub

  Public Sub DoSomething(ByVal a() As Long)
    Dim i As Integer = a.Length - 1
    Dim j As Integer = 0
a4:
    If a(j) > a(j + 1) Then GoTo 3
    j = j + 1
    If j = i Then GoTo 9
    GoTo a4
9:
    j = 0
    i = i - 1
    If i = 0 Then GoTo 5
7:
    GoTo a4
3:
    Dim t As Long
    t = a(j)
    a(j) = a(j + 1)
    a(j + 1) = t
    GoTo 7
5:
  End Sub

As you can see, quite clear and concise. I would say that it's a pretty good example of 'bad' code. Feel free to copy it...maybe find the bug.

[TheBarret]

The 'Goto is bad' is really a rule. Generally, the use of goto implies a programmer with limited experience, is unwilling to listen, is simply resting on their laurels, or all of the above.
[/CODE]

As you can see, quite clear and concise. I would say that it's a pretty good example of 'bad' code. Feel free to copy it...maybe find the bug.

Prob all right but not of use to me atm because this has not very much todo with the project i am doing.

[TheBarret]

Replaced alote since last time, heres what i did.

- Parser replaced with a lexer (so much easier!)
- Functions accept parameters instead of compound variables
- Functions have theire own variable tables
- Global variables
- Do-loops (until/while/inf) statement are using the same comparision class as the if-then-else
- if-then-else supports (true/false or 1/0 or simple comparision methods)
- Line seperators multiple statements in one line
- Self made functions automaticly become a function within the engine and can be called from anywhere
- and alote of fine tuning...

Screen shot: