Detailed Code Improvements

    As part of the VBUC’s advanced functionalities, the tool makes the converted code more .NET-like, while also improving aesthetic aspects.

    Some of the enhancements are related to code simplifications. The following examples show some of these cases:

    Source pattern Target .NET pattern
    if <cond> then return true else return false return <cond>
    if <cond> then <var> = true else <var> = false <var> = <cond>
    if <cond> then <var> = false else <var> = true <var> = !<cond>
    <booleanexpression> compared to true or false [!] <booleanexpression>
    Operations simplifications like:
    (<exp> + 1) > 0
    <exp> >= 0
    !(!<expression>) <expression>
    Arithmetic simplifications Several simplifications like:
    (<expression> + 1) - 1 => <expression>
    Err.Raise throw new Exception()

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    Other enhancements are related to library members that were previously converted to the .NET Visual Basic 6 Compatibility Library. The VBUC converts them to .NET Framework native libraries, as shown in the following table:

    Source pattern Target .NET pattern
    <timer_reference>.Interval compared to 0 patterns. Patterns of <timer_reference>.Enabled
    Dir(<path>, vbDirectory) compared to empty string. [!] System.IO.Directory.Exists(<filename>)
    vb.App.LogEvent System.Diagnostics.EventLog.WriteEntry
    VBA.FileSystem.Kill System.IO.File.Delete
    vba.FileSystem.FileCopy System.IO.File.Copy
    Different patterns of p.ToString(...)
    VBA.DateTime.Date Uses of System.DateTime.Now
    VBA.DateTime.DateValue Uses of System.DateTime.Parse
    where “p” can be a:
    - numeric
    - boolean
    - date
    - string
    - object
    numeric -> p.Equals(0)
    boolean -> p.Equals(false)
    date -> p.Equals(DateTime.FromOADate(0))
    string -> p.IsNullOrEmpty()
    object -> p.Equals(param,Nothing)
    VBA.Strings.Split(...) Various patterns of <string-object>.Split(…)
    VBA.VbMsgBoxResult Patterns of System.Windows.Forms.DialogResult
    VBA.VbDayOfWeek System.FirstDayOfWeek
    Uses of <str-object>.Substring(…)
    VBA.Constants.<char-const> Strings.Chr(<value>) / chr(13)
    File IO operations Converted using System.IO namespace

    If-ElseIf Block to Switch Block

    The VBUC detects If-ElseIf blocks with all its conditions, comparing the same expression against different values and converting them to a more natural Switch block.

    Replacement of “for” Loops by “foreach” Loops

    When VB6 For loops iterate over collections and some arrays, VBUC upgrades the statement to .NET ForEach statements, applying the necessary transformations to the collection/array references inside the For body and the counter variables.

    Counter variables that are no longer needed after the Foreach transformation are removed from the resulting code block.

    Unify Code Blocks

    Some classes in VB6 have two events that correspond to one unique event in the corresponding .NET class. In those cases, the bodies of the two events are merged to achieve the same behavior.

    Some examples of these transformations are:

    • MSComctlLib.StatusBar PanelClick and PanelDblClick events
    • MSComctlLib.ListView ItemClick and Click events

    New Objects Declaration

    This rule allows adding the variable initialization value to its declaration:


    Dim _myvar as MyType
    ... <Code which doesn’t reference _myvar>
    _myvar = InitValue 


    MyType _myvar = InitValue;
    ... <Code which doesn’t reference _myvar>

    Automatic “import” Clause Generation

    Besides the option of generating references to the .NET library elements by using their fully qualified names, the VBUC introduces an additional transformation stage that recognizes fully qualified names and simplifies them while automatically generating the necessary import / using causes.

    This new feature makes the converted code look much better providing an improved readability and maintainability.