Re: [boost] boost::noncopyable errors are difficult to diagnose on MSVC

6 Nov 2009

      On Fri, Nov 6, 2009 at 1:17 PM, Emil Dotchevski
<emildotchevski@gmail.com> wrote:
...
On Fri, Nov 6, 2009 at 9:44 AM, Zachary Turner <divisortheory@gmail.com> wrote:
...
Is there anything that can be done to improve the error messages generated
by the compiler when a copy fails to be made due to a boost::noncopyable?
Easy cure is to spell out the private declarations for the copy
constructor and the assignment operator "by hand". We all know that
this spells "non-copyable".
Because of C++0x deleted functions, the idiom for noncopyable is going
to change.

    class foo {
          foo( const foo & ) = delete;
          foo & operator =( const foo & ) = delete;
          ...
    };

Maybe Boost should have a macro, say BOOST_NONCOPYABLE(T), that would
generate the above for C++0x compilers, and the following for
pre-C++0x compilers:

    class foo {
          foo( const foo & );
          foo & operator =( const foo & );
          ...
    };

What the user would actually write would be:

    class foo {
          BOOST_NONCOPYABLE(foo)
          ...
    };

Another approach would be for the user to write:

    class foo {
          foo( const foo & ) BOOST_DELETED_FUNC;
          foo & operator =( const foo & ) BOOST_DELETED_FUNC;
          ...
    };

For 0x it would generate =delete while for non-0x it would generate nothing.

--Beman

Re: [boost] boost::noncopyable errors are difficult to diagnose on MSVC

Beman Dawes