Re: [boost] Move semantics for std::string?

Subject: Re: [boost] Move semantics for std::string?
From: Roman Perepelitsa (roman.perepelitsa_at_[hidden])
Date: 2012-02-17 11:24:50

2012/2/17 Robert Dailey <rcdailey_at_[hidden]>

>
> > Simplified RVO rules: If all return statements in a function refer to the
> > same local variable OR if a function returns an ravlue in all cases, the
> > copy can (and in practice will) be elided.
> >
> > // RVO-enabled: always returns the same local variable.
> > string foo() {
> >  string res;
> >  if (flag) {
> >    res = "hello";
> >    return res;
> >  } else {
> >    res = "bye";
> >    return res;
> >  }
> > }
> >
> > // RVO-enabled: always returns a temporary.
> > string foo() {
> >  if (flag)
> >    return "hello";
> >  else
> >    return "bye";
> > }
> >
> > It's a good practice to make all functions you write RVO-enabled.
>
>
> So all of these functions are functionally equivalent to simply
> constructing a std::string object in the calling scope?

Yes.