Is polymorphism possible in vba function declarations?

Question

Hello super awesome forum contributors,

Does anyone know how to make the following work in Excel?

I'd like to have a function

function param_overload(var_overloaded as Range) as string

   param_overload ="var_overloaded_as_param"

end function

function param_overload(var_overloaded as string) as string

    param_overload = "var_overloaded as string"

end function

I get an ambiguous name definition error in VBA.

any ideas are welcome.

Answer 1

Dave,  thanks for the suggestions.  On the track of the variant parameter, how do you type check a variant object to know what it actually is.

The VBA help documentation has not been so helpful (as you said above :) )

You can use the TypeName or VarType functions, or you can test its TypeOf like this...

If TypeOf YouVariant Is "TextBox" Then

depending on how you want to structure your code.

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Answer 2

Pass it a variant and have your code check to see what it is.

And while you're reading VBA's help <hehe>, remember to look at paramarray under

the help for the Function Statement.

SantaMonicaMike wrote:

i've seen some vendors provide functions where they use the same name in the function but you have the option of using a parameter that is a string or a parameter that is a range.  How is this possible then?

--

Dave Peterson

Answer 3

Although I think that this is usually a bad thing to do, you could put the

functions in separate modules in the same project.

If you're calling the UDF from a formula in a cell in a worksheet, just prepend

the module name onto the function call:

=Module1.param_overload(a1)

or

=Module1.param_overload(a1)

Same kind of thing if you're calling the function in code from a different

module.  (If the calling code is in the same module, then the function in that

module will be used.)

Option Explicit

Sub aa()

    dim myStr as string

    mystr = param_overload(activesheet.range("a1")

End Sub

Again, I wouldn't do this.  You may be vigilant today, but maybe not so much

tomorrow -- or the poor soul that will have to update your code.

SantaMonicaMike wrote:

Hello super awesome forum contributors,

Does anyone know how to make the following work in Excel?

I'd like to have a function

function param_overload(var_overloaded as Range) as string

   param_overload ="var_overloaded_as_param"

end function

function param_overload(var_overloaded as string) as string

    param_overload = "var_overloaded as string"

end function

I get an ambiguous name definition error in VBA.

any ideas are welcome.

--

Dave Peterson

Answer 4

i've seen some vendors provide functions where they use the same name in the function but you have the option of using a parameter that is a string or a parameter that is a range.  How is this possible then?

Answer 5

That is because in Excel VBAA you can have at most one function named param_overload

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gsnu201005