Method "Overload" Example: A Debugging Aid

Don't let the word "overload" bother you. We won't be "overdoing" anything. In RB, "overload" means giving more than one method (i.e., Function or Sub) the same name, but with a different number or different types of passed parameters. [Originally I had said "(or different return type)," but that was wrong - see the helpful comment by Will Leshner smong the comments to this blog entry.] Many languages do not allow you to do that, but REALbasic does.

Let me give as an example something I use regularly as a debugging aid. Now, many people use MsgBox to help in debugging by displaying the value of a particular variable at a certain point in the Project. For example, suppose you want to check on the value of the integer XMLLineNumber. You can insert the following at the desired place in your program:

MsgBox "XMLLineNumber" + EndOfLine + Str(XMLLineNumber)

(The "EndOfLine" is there to put the value on a new line in the MsgBox.)

Or suppose you want to check on the value of the string XMLLine. You can insert the following:

MsgBox "XMLLine" + EndOfLine + "|" + XMLLine + "|"

(The "|" is used so that you can see if there is any blank space at the beginning or end of XMLLine.)

Or suppose you want to check on the value of the Boolean IsSource. You can do that with this:

If IsSource Then MsgBox "IsSource" + EndOfLine + "True" 
          Else MsgBox "IsSource" + EndOfLine + "False"

It's a headache, however, to have to use three different formats (integer, string, and Boolean) and remember which one to use for which situation.

Instead of doing that, let's define (and "overload") a Function called S, all forms of which return a String (my reason for choosing to call it "S"), but which respond to different types of passed parameters.

First, define S with an integer Param1 as a passed parameter in this way:

Function S (Param1 As Integer) As String
    Return EndOfLine + Str(Param1) + EndOfLine
End Function

Second, define S with a string Param1 as a passed parameter in this way:

Function S (Param1 As String) As String
     Return EndOfLine + "|" + Param1 + "|" + EndOfLine
End Function

Third, define S with a Boolean Param1 as a passed parameter in this way:

Function S (Param1 As Boolean) As String
     If Param1 Then Return "True" Else Return "False"
End Function

Once this is done, you can just use S, regardless of which of the three types of passed parameter we have in mind. Example:

MsgBox "XMLLineNumber" + S(XMLLineNumber)

MsgBox "XMLLine" + S(XMLLine)

MsgBox "IsSource + S(IsSource)

or even

MsgBox "XMLLineNumber" + S(XMLLineNumber) + "XMLLine" 
          + S(XMLLine) + "IsSource" + S(IsSource)

Try it -- you may like it!

Barry Traver

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Blog Home Page: http://traverrb.blogspot.com/

Programs and Files Discussed in the Blog: http://traver.org/traverrb/