[python-win32] Byte arrays and COM

[Dave Cross]

Hi All,
 
I'm tying myself in knots trying to pass a byte array between a C++ DLL
and python.
 
The simplified IDl looks like this:
    HRESULT Test([in,out] int *len, [in,out, size_is(*len)] byte* outp);
 and the implementation does this:
    STDMETHODIMP CComTestObj::Test(int *len, unsigned char* outp)
    {
     printf("input param is <%d>  %s at  %lx,\n",*len, outp, outp);
     strncpy((char*)outp,"TEST",*len);
     return S_OK;    
    }

Makepy generates the following:
 
     def Test(self, len=defaultNamedNotOptArg,
outp=defaultNamedNotOptArg):
          """method Test"""
          return self._ApplyTypes_(6, 1, (24, 0), ((16387, 3), (16401,
3)), u'Test', None,len, outp)
 
I interpret (16387,3) as VT_I4, ByREF, In & Out and (16401,3) as VT_UI1,
ByRef In & Out so this looks OK to me.
 
However when I call it like this:
 
     object = win32com.client.Dispatch("ComTest.ComTestObj.1")
     test = create_string_buffer("Hello")
     print "Test is ", object.Test(6,addressof(test))

Then
          a) The C++ routine gets an address that doesn't map to the
input string 
and     b) the returned value is (3, 84)
 
Any ideas as to where I'm going wrong would be much appreciated.
 
Dave.
 
 

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