Re: [Quantlib-dev] shared_ptr in Error class

[Bojan N. <bo...@bn...>]

Luigi Ballabio <lui...@gm...> writes:

> the compiler (well, gcc at least) will complain that the copy  
> constructor is private at the "throw" line.

All compilers should do the same:

,---- From http://www.open-std.org/jtc1/sc22/open/n2356/except.html
|  When
|   the thrown object is a class object, and the copy constructor used  to
|   initialize  the  temporary copy is not accessible, the program is ill-
|   formed (even when the temporary object could otherwise be eliminated).
|   Similarly,  if  the  destructor for that object is not accessible, the
|   program is ill-formed (even when the temporary object could  otherwise
|   be eliminated).
| 
`----

However, this is not the same as saying that the copy constructor is
actually always invoked because of the following statement

,---- From http://www.open-std.org/jtc1/sc22/open/n2356/except.html
| If the use of the temporary object can be eliminated without
|   changing the meaning of the program except for the execution  of  con-
|   structors  and  destructors  associated  with the use of the temporary
|   object (_class.temporary_), then the exception in the handler  can  be
|   initialized  directly with the argument of the throw expression.
`----

So, in this program the copy constructor is (I believe) not invoked:

#include <iostream>

class Foo {
public:
  Foo() {};
  Foo(const Foo&) 
  {
    std::cout<<"copy ctr"<<std::endl;
  }
private:

};

int main() {
     try 
     {
         
       throw Foo();
     }
     catch (const Foo &f) 
     {
       std::cout<<"in the handler"<<std::endl;
     }
     return 0;
}



Best,
Bojan

-- 
Bojan Nikolic          ||          http://www.bnikolic.co.uk