Microsoft KB Archive/175215

= ACC97: Error When Object Methods Rely On Optional Arguments =

Article ID: 175215

Article Last Modified on 1/22/2007

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APPLIES TO


 * Microsoft Access 97 Standard Edition

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This article was previously published under Q175215



Moderate: Requires basic macro, coding, and interoperability skills.



SYMPTOMS
If an object's method within a subroutine or a function uses the optional arguments allowed by the subroutine or the function, and one or more of the optional arguments are excluded at the time that the subroutine or the function is called, one of the following run-time errors can occur:

Run-time error '13':

Type mismatch

  -or-

Run-time error '2493':

This action requires an Object Name argument.



CAUSE
The object's method is expecting one or more of its arguments to have some value, and one of the arguments has either been assigned an unknown value, or the value has been excluded altogether.



RESOLUTION
Functions such as IsMissing or IsNull within Visual Basic for Applications can be used to check for any excluded optional arguments. Within the subroutine or the function that is called, programmatically test to see if one or more of the optional arguments was excluded. For example:

  Type the following two procedures into a new module:

Sub Prog1(Optional a, Optional b, Optional c)       If IsMissing(a) Then a = acDefault If IsMissing(b) Then b = "" If IsMissing(C) Then c = acSavePrompt DoCmd.Close a, b, c   End Sub

Sub Prog2(Optional a As Long, Optional b As String, Optional c As Long) If a = 0 Then a = acDefault If IsNull(b) Then b = "" If C = 0 Then c = acSavePrompt DoCmd.Close a, b, c   End Sub  Press CTRL+G to open and move focus to the Debug window.  Type the following line in the Debug window, and then press ENTER:

    Prog1   Type the following line in the Debug window, and then press ENTER:

    Prog2 </li></ol>

<div class="moreinformation_section">

MORE INFORMATION
If you have programmatically specified that one or more arguments of a method should be used, and you do not supply an argument at run time or you do not supply a valid value for an argument, you will receive the run-time error.

To illustrate this point, the "Steps to Reproduce Behavior" section will use the Close method of the DoCmd object within a subroutine, where the subroutine allows for optional arguments. However, when the subroutine is called, the optional arguments are excluded in order to generate the run-time error.

Steps to Reproduce Behavior
<ol> Open the sample database Northwind.mdb.</li>  Create a new module and type the following procedure:

Sub Prog(Optional a, Optional b, Optional c)        DoCmd.Close a, b, c      End Sub </li> Save the module as modTest.</li> Press CTRL+G to open and move focus to the Debug window.</li>  Type the following line in the Debug window, and then press ENTER:

<pre class="fixed_text">     Prog

Note that you receive the "Type Mismatch" run-time error. </li>  Modify the arguments within the subroutine as follows:

Sub Prog(Optional a As Long, Optional b As String, Optional c As Long) </li> Repeat steps 3 through 5.

Note that you receive the "This action requires an Object Name argument" run-time error.</li></ol>

Additional query words: run time error 13 run time error 2493

Keywords: kberrmsg kbprb KB175215

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