[python-win32] FireEvent : comtypes work but win32com fails, why?

[June Kim]

What roundabouts would you recommend to make FireEvent work with
pywin32 module? My clients are mostly installed with pywin32, and
switching to comtypes is a risk now.


2008/6/26, Mark Hammond <mhammond at skippinet.com.au>:
> > I do not know where you see the VT_VARIANT.
> >
> > Here is the IDL defn:
> >
> >             [id(0x80010452)]
> >             VARIANT_BOOL FireEvent(
> >                             [in] BSTR bstrEventName,
> >                             [in, optional] VARIANT* pvarEventObject);
> >
> > and the comtypes wrapper snippet:
> >     DISPMETHOD([dispid(-2147417006)], VARIANT_BOOL, 'FireEvent',
> >                ( ['in'], BSTR, 'bstrEventName' ),
> >                ( ['in', 'optional'], POINTER(VARIANT),
> > 'pvarEventObject' )),
>
> Yeah - when win32com gets the type info, it is told the variable is a
> "VT_BYREF|VT_VARIANT - eg:
>
>        def FireEvent(self, bstrEventName=defaultNamedNotOptArg,
> pvarEventObject=defaultNamedOptArg):
>                return self._oleobj_.InvokeTypes(-2147417006, LCID, 1, (11,
> 0), ((8, 1), (16396, 17)),bstrEventName
>                        , pvarEventObject)
>
> 16396, 17 == (VT_BYREF|VT_VARIANT, PARAMFLAG_FOPT|PARAMFLAG_FIN)
>
> so pythoncom's type converter sees this type tuple, and tries to create a
> variant with the exact type specified.  It would seem I must treat
> VT_VARIANT as a special case (the returned vartype in that case can be
> anything and is driven by the type of the param)
>
> > > Is that correct?  If so, I guess I should give that a whirl and
> > > hope nothing else in the test suite breaks ;)
> >
> > Thats what test suites are for...
>
> I'm more worried that the change will break something that some obscure
> program relies on (ie, I hope the test suite shows the change is backwards
> compatible)
>
> > PS: Do you know the answer to the question that I posted in the other
> > reply to this
> > thread (short version: does pywin32 use IDispatchEx)?
>
> It doesn't in win32com.client (ie, not when calling objects, as in this
> example).  win32com.server does IDispatchEx though (mainly as IE itself is
> one of the only IDispatchEx users around.  IDispatchEx was desgined for
> ActiveScripting to offer javascript style semantics to an IDispatch-ish
> interface.
>
> Cheers,
>
> Mark
>
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