Groups | Search | Server Info | Keyboard shortcuts | Login | Register [http] [https] [nntp] [nntps]

Groups > comp.lang.c++ > #7946

Re: static_cast, cast operator, and constructors.

Show all headers | View raw

On 07/19/11 10:46 AM, Noah Roberts wrote:
> Considder:
>
> struct ObjectA
> {
>     ObjectA(ObjectA const&);
>
>     template<  typename T>
>     ObjectA(T const&);
>
>     void fun() const;
> };
>
> struct ObjectB
> {
>     operator ObjectA () const;
> };
>
> static_cast<ObjectA>(an_object_b).fun();
>
> Which constructor does the standard specify will be called during the
> static_cast: copy or template?

Is the code complete?  The only option is the template.

> Behavior I am seeing is that the templated version is called and then
> bases are called on the result of the cast operator.
>
> Is there a way to explicitly call the cast operator or is that what I'm
> supposedly doing?

Specialise the template constructor for ObjectB.

template <>
ObjectA::ObjectA<ObjectB>(ObjectB const&)
{
  std::cout << "special" << std::endl;
  }

-- 
Ian Collins

Back to comp.lang.c++ | Previous | Next — Previous in thread | Next in thread | Find similar | Unroll thread

Thread

static_cast, cast operator, and constructors. Noah Roberts <dont@email.me> - 2011-07-18 15:46 -0700
  Re: static_cast, cast operator, and constructors. Ian Collins <ian-news@hotmail.com> - 2011-07-19 11:29 +1200
    Re: static_cast, cast operator, and constructors. Noah Roberts <dont@email.me> - 2011-07-18 16:44 -0700
      Re: static_cast, cast operator, and constructors. Ian Collins <ian-news@hotmail.com> - 2011-07-19 11:57 +1200
        Re: static_cast, cast operator, and constructors. Jorgen Grahn <grahn+nntp@snipabacken.se> - 2011-07-19 13:12 +0000
          Re: static_cast, cast operator, and constructors. Noah Roberts <dont@email.me> - 2011-07-19 09:26 -0700
            Re: static_cast, cast operator, and constructors. Jorgen Grahn <grahn+nntp@snipabacken.se> - 2011-07-20 18:52 +0000
  Re: static_cast, cast operator, and constructors. James Kanze <james.kanze@gmail.com> - 2011-07-20 12:53 -0700

csiph-web