Why do I receive an error when trying to invoke a method on an object that has reference or optional arguments?

Why do I receive an error when trying to invoke a method on an object that has reference or

optional arguments?

Consider a COM object that has a method with following signature:

 [id(1), helpstring("method AllinOne")] HRESULT AllinOne([in] double db, [out] BSTR* strout, 

 [in, out] long* ln, [in,optional] BSTR strin, [out, optional] VARIANT* var, 

 [out,retval] BOOL* bret);

This is the code I use in MATLAB:

h=actxserver('TestServer.ArgTest.1');

[a,b,c,d] = invoke(h, 'AllinOne', 5.57, 10, 'test')

But MATLAB returns:

 ??? No method with matching signature.

As you can see, MATLAB incorrectly thinks the signature for the AllinOne method is as follows:

invoke(h) 

AllinOne = [int32, string, int32] AllinOne(handle, double, int32, Variant(Optional))

Answer 1

[MathWorks Support Team]

This problem has been fixed in MATLAB 6.5.1 (R13SP1). If you are using a previous version, read the following:

This issue has been addressed in updated versions of comcli.dll and newprogid.m. With this fix,

the correct signature is seen by MATLAB:

invoke(h) 

AllinOne = [int32, string, int32, Variant] AllinOne(handle, double, int32, Variant(Optional))

You can now invoke methods with optional or reference arguments:

[a,b,c,d] = invoke(h, 'AllinOne', 5.57, 10, 'test')

a =

       1

b =

[out] returned

c =

       20

d =

[out,optional] returned

The updated versions of comcli.dll and newprogid.m should replace the current versions in your MATLAB installation. Both are available from the related solution below.