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POWhat's the Matlab equivalent of NULL, when it's calling COM/ActiveX methods?
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  1. POWhat's the Matlab equivalent of NULL, when it's calling COM/ActiveX methods?
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    copied!<p>I maintain a program which can be automated via COM. Generally customers use VBS to do their scripting, but we have a couple of customers who use <b>Matlab's ActiveX support</b> and are having trouble <b>calling COM object methods with a NULL parameter</b>.</p> <p>They've asked how they do this in Matlab - and I've been scouring <a href="http://www.mathworks.com/access/helpdesk/help/techdoc/matlab_external/bq4epvg-1.html" rel="noreferrer">Mathworks' COM/ActiveX documentation</a> for a day or so now and can't figure it out.</p> <p>Their example code might look something like this:</p> <pre><code>function do_something() OurAppInstance = actxserver('Foo.Application'); OurAppInstance.Method('Hello', NULL) end </code></pre> <p>where <code>NULL</code> is where in another language, we'd write <code>NULL</code> or <code>nil</code> or <code>Nothing</code>, or, of course, pass in an object. The problem is this is optional (and these are implemented as optional parameters in most, but <i>not all</i>, cases) - these methods expect to get NULL quite often.</p> <p>They tell me they've tried <code>[]</code> (which from my reading seemed the most likely) as well as <code>''</code>, <code>Nothing</code>, <code>'Nothing'</code>, <code>None</code>, <code>Null</code>, and <code>0</code>. I have no idea how many of those are even valid Matlab keywords - certainly none work in this case.</p> <p>Can anyone help? What's Matlab's syntax for a null pointer / object for use as a COM method parameter?</p> <p><strong>Update:</strong> Thanks for all the replies so far! Unfortunately, none of the answers seem to work, not even <code>libpointer</code>. The error is the same in all cases:</p> <p><code>Error: Type mismatch, argument 2</code></p> <p>This parameter in the COM type library is described in RIDL as:</p> <pre><code> HRESULT _stdcall OurMethod([in] BSTR strParamOne, [in, optional] OurCoClass* oParamTwo, [out, retval] VARIANT_BOOL* bResult); </code></pre> <p>The coclass in question implements a single interface descending from IDispatch.</p>
 

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