Linker error - VS2005 thinks it's a function declaration?

[Lawrence Spector]

Base base;
BaseWrap& baseWrap(reinte rpret_cast<Base Wrap&>(base));
boost::python:: object obj(boost::shar ed_ptr<BaseWrap >(&baseWrap)) ; //
Compile error

Results in this error:

1>PythonPassRef erence.obj : error LNK2019: unresolved external symbol
"class boost::python:: api::object __cdecl obj(class
boost::shared_p tr<struct BaseWrap&)" (?obj@@YA?
AVobject@api@py thon@boost@@AAV ?$shared_ptr@UB aseWrap@@@4@@Z)
referenced in function _main

My first thought is somehow that looks like a function declaration
instead of creating an object on the stack and instantiating it. If I
remove the shared_ptr, the error goes away.

In case it helps, here's a few more details.

boost::python:: object has the following constructor:

// explicit conversion from any C++ object to Python
template <class T>
explicit object(
T const& x
# if BOOST_WORKAROUN D(BOOST_MSVC, < 1300)
// use some SFINAE to un-confuse MSVC about its
// copy-initialization ambiguity claim.
, typename mpl::if_<is_pro xy<T>,int&,int> ::type* = 0
# endif
)
: object_base(obj ect_base_initia lizer(x))
{
}

boost::shared_p tr<Thas the following constructor:

template<class Y>
explicit shared_ptr( Y * p ): px( p ), pn( p ) // Y must be
complete
{
boost::detail:: sp_enable_share d_from_this( pn, p, p );
}

Any tips on how to solve this would be greatly appreciated. I'm
probably overlooking something obvious.

Thanks in advance,

Lawrence

[Victor Bazarov]

Lawrence Spector wrote:

Base base;
BaseWrap& baseWrap(reinte rpret_cast<Base Wrap&>(base));
boost::python:: object obj(boost::shar ed_ptr<BaseWrap >(&baseWrap)) ; //
Compile error

Results in this error:

1>PythonPassRef erence.obj : error LNK2019: unresolved external symbol
"class boost::python:: api::object __cdecl obj(class
boost::shared_p tr<struct BaseWrap&)" (?obj@@YA?
AVobject@api@py thon@boost@@AAV ?$shared_ptr@UB aseWrap@@@4@@Z)
referenced in function _main

My first thought is somehow that looks like a function declaration
instead of creating an object on the stack and instantiating it. If I
remove the shared_ptr, the error goes away.
Any tips on how to solve this would be greatly appreciated. I'm
probably overlooking something obvious.

You are overlooking something, but it's not that obvious. Your 'obj'
declaration is similar to

double obj(int(&blah)) ;

Care to parse it? A hint: the parentheses around &blah don't matter.

....

Give up? It's the same as

double obj(int &blah);

Look familiar? It's a function declaration!

How do you prevent this from being treated as a function declaration?
Put extra parentheses around the "argument":

double obj((int(&blah) ));

In your case:

boost::python:: object obj( (boost::shared_ ptr<BaseWrap>(& baseWrap)) );

V
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