Re: Collection Copy Policy in ATL8-vs2005

From:
"SvenC" <SvenC@community.nospam>
Newsgroups:
microsoft.public.cn.vc++,microsoft.public.vc.atl,microsoft.public.vc.stl
Date:
Tue, 19 Sep 2006 18:43:24 +0200
Message-ID:
<#KI46qA3GHA.1624@TK2MSFTNGP03.phx.gbl>
Hi Townee,

"Townee" <zhp80@sina.com> wrote in message
news:eIMBir82GHA.3464@TK2MSFTNGP03.phx.gbl...

Thanks
I know that is is a problem of const correctness.

in VC 2005
template <.....>
class ICollectionOnSTLImpl:public T
{
....
....
STDMETHOD(get_Item)(long Index, ItemType* pvar)
{
......
......
CollType::const_iterator iter = m_coll.begin();
......
.....

I insert const on any position :

typename typedef const ContainerType::value_type SourceType;

or

static HRESULT copy(InterfaceType** pTo, const SourceType* pFrom )

{
 return _CopyInterface<InterfaceType>::copy(pTo, &(pFrom->second));
}

To compile every mode is
error C2664: 'ATL::_CopyInterface<T>::copy' : cannot convert parameter 2
from 'IObjA *const *__w64 ' to 'IObjA **'


_CopyInterface's copy method seems to be not const correct. You have to
const_cast the second parameter or change the ATL code to make the second
parameter const correct. To not depend on such a change which you would nee
on any machine you install ATL and use that code, try:

return _CopyInterface<InterfaceType>::copy(pTo,
const_cast<IObjA**>(&(pFrom->second)));

I'm not sure about your typedefs, maybe you want to use
const_cast<SourceType*>(...)

--
SvenC

Where the const is inseted will is RIGHT?
Thanks in advance,
ZHP.Henry

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