Problem with SAFEARRAY as property accessors.

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Ahmad Jalil Qarshi - 24 Mar 2005 15:51 GMT

i want to store binary data into my property. i read earlier positing on
"microsoft.public.dotnet.languages.vc" group with subject as SAFEARRAY in
attributed ATL7 Project. i followed the same approach but unfortunately i
failed to do that.
i declared the property accessors as follow in my idl file.

[propget, id(2), helpstring("property Data")] HRESULT Data([out, retval,
satype(byte)] SAFEARRAY * *pVal);
[propput, id(2), helpstring("property Data")] HRESULT Data([in,
satype(byte)] SAFEARRAY * newVal);

when i compile code i get following error.
error MIDL2025 : syntax error : expecting ] or , near "satype".

any body there to help me.

Thanks in advance.

Ahmad Jalil Qarshi

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Igor Tandetnik - 24 Mar 2005 15:57 GMT

> [propget, id(2), helpstring("property Data")] HRESULT Data([out,
> retval, satype(byte)] SAFEARRAY * *pVal);
[quoted text clipped - 3 lines]
> when i compile code i get following error.
> error MIDL2025 : syntax error : expecting ] or , near "satype".

In IDL, the syntax is different:

[propget, id(2), helpstring("property Data")]
HRESULT Data([out, retval] SAFEARRAY(BYTE) *pVal);
[propput, id(2), helpstring("property Data")]
HRESULT Data([in] SAFEARRAY(BYTE) newVal);

The syntax in your post is used in a .cpp file when building an
attributed project.

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With best wishes,
Igor Tandetnik

With sufficient thrust, pigs fly just fine. However, this is not
necessarily a good idea. It is hard to be sure where they are going to
land, and it could be dangerous sitting under them as they fly
overhead. -- RFC 1925

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Ahmad Jalil Qarshi - 25 Mar 2005 12:54 GMT

Thanks Igor!
i have done that according to your instruction. but still i get same error
twice which is here under.

error C2259: 'CComObject<class CTestLoadObj>' : cannot instantiate abstract
class due to following members:
c:\program files\microsoft visual
studio\vc98\atl\include\atlcom.h(1823) : while compiling class-template
member function 'long __stdcall ATL::CComCreator<class ATL::CComObject<class
CTestLoadObj> >::CreateInstance(void *,const struct _GUID
&,void ** )'

could you plz tell me how to define these properties in .cpp file also.
i suppose that it would be like that:
STDMETHODIMP CTestLoadObj::get_Data(SAFEARRAY *pVal)
{
}
STDMETHODIMP CTestLoadObj::put_Data(SAFEARRAY pVal)
{
}
but i m sure that i m wrong that's y i m getting errors. please guide me.
Thanks in advance.
Ahmad Jalil Qarshi

> > [propget, id(2), helpstring("property Data")] HRESULT Data([out,
> > retval, satype(byte)] SAFEARRAY * *pVal);
[quoted text clipped - 21 lines]
> land, and it could be dangerous sitting under them as they fly
> overhead. -- RFC 1925

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Igor Tandetnik - 25 Mar 2005 16:11 GMT

> error C2259: 'CComObject<class CTestLoadObj>' : cannot instantiate
> abstract class due to following members:
[quoted text clipped - 13 lines]
> {
> }

A SAFEARRAY(Whatever) parameter in IDL becomes SAFEARRAY* in C++.
SAFEARRAY(Whatever)* becomes SAFEARRAY**, and so on. In other words, in
C++ you always specify one extra level of indirection compared to IDL
syntax.

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Ahmad Jalil Qarshi - 25 Mar 2005 16:35 GMT

Thanks again!
i have done that. its compiled now successfully. but my object is not
persisting this safearray, whereas other properties of this object persist.
Isn't it possible to persist SAFEARRAYs.
Thanks.
Ahmad Jalil Qarshi

> > error C2259: 'CComObject<class CTestLoadObj>' : cannot instantiate
> > abstract class due to following members:
[quoted text clipped - 26 lines]
> land, and it could be dangerous sitting under them as they fly
> overhead. -- RFC 1925

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Igor Tandetnik - 25 Mar 2005 16:39 GMT

> i have done that. its compiled now successfully. but my object is not
> persisting this safearray, whereas other properties of this object
> persist. Isn't it possible to persist SAFEARRAYs.

ATL persistence implementation (IPersistStreamInitImpl et al) indeed
does not support safearrays. You will have to write your own.

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Problem with SAFEARRAY as property accessors.

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