vb6 ismissing function
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Thread: vb6 ismissing function

  1. #1
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    vb6 ismissing function (resolved)

    Hi All,

    I'm just starting .NET. In vb6 there was a function is missing i.e.

    public function deleteme(optional fred as variant)
    if ismissing(fred) ............

    What should the syntax be in .NET2003 since it doesn't support isMissing.

    Thanks
    Last edited by Bill Crawley; October 1st, 2004 at 09:14 AM. Reason: resolved
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  2. #2
    Join Date
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    Re: vb6 ismissing function

    You should no longer use optional parameters. If you need to use different parameters at different times, make overloads of the function. ie:

    Public Function SomeFunction(param1 as string) as string
    Public Function SomeFunction(Param1 as string, Param2 as integer) as string
    Public Function SomeFunction(Param1 as string, Param2 as integer, Param3 as long) as String

    etc.

  3. #3
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    Re: vb6 ismissing function

    DSJ is correct!

    While there are "some" reasons for using optional arguments [vastly depreciated] there is no reliable way to determine if a parameter has been specified

    A procedure cannot detect at run time whether a given argument has been omitted or the calling code has explicitly supplied the default value. If you need to make this distinction, you can set an unlikely value as the default.
    Overloaded methods (which were not previously available) are a much better way to go. [espcially if other languages may eventually want to access the routine]
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