Re: [boost] Heads up - string_ref landing

Subject: Re: [boost] Heads up - string_ref landing
From: Gottlob Frege (gottlobfrege_at_[hidden])
Date: 2012-12-12 12:30:14

On Wed, Dec 12, 2012 at 10:49 AM, Rob Stewart <robertstewart_at_[hidden]>wrote:

> >>>
> >>> std::string does not have a 'null' state.
> >>
> >> It's the state represented by empty().
> >
> > I am not sure it is so certainly accepted by all.
>
> It is the logical interpretation. It indicates whether the string is
> non-empty. I don't see any other generally useful interpretation, do you?
>
>

Qt's QString has both empty() and isNull() and they are not always the
same.  Basically empty() is a zero-byte string, but null is a
never-been-set-or-allocated string.
ie

QString name = database.get("Name");

name.empty() == true  means the Name field was empty
name.isNull() == true  means the Name field doesn't exist in the database.

Somewhat like optional<string>.

I am NOT saying whether this is a good thing.  Just a widely known example
of interpretation.

Tony