Re: [boost] [Operators] Update, const-correctness and operator chaining

Subject: Re: [boost] [Operators] Update, const-correctness and operator chaining
From: Eric Niebler (eniebler_at_[hidden])
Date: 2013-07-01 18:13:16

On 13-07-01 02:42 PM, Andrew Ho wrote:
> This allows this to be done:
> 
> val1 + val2 = val3;
> 
> changing the return type to const T would allow the compiler to catch
> this, but now doing val1 + val2 + val3 must always use copy semantics
> instead of move semantics.

Two answers: tell your users not to do a+b=c, or tell authors of value
type to mark a rvalue overload of operator= "=delete", like:

  string & operator=(string &&) && = delete;
  string & operator=(const string &) && = delete;

Nobody does this, I'm guessing, because it's just not a problem in
practice. I've personally never seen this mistake in real code, and
wouldn't worry too much about it.

-- 
Eric Niebler
Boost.org