Re: [lmi] [PATCH] C++ m11n: range-based for loops

[Vadim Zeitlin]

On Tue, 17 Jan 2017 01:59:59 +0000 Greg Chicares <address@hidden> wrote:

GC> On 2017-01-16 17:20, Vadim Zeitlin wrote:
...
GC> >  BTW, I find it useful to have some kind of "once only" helper class, e.g.
GC> [...]
GC> > and then use it like this:
GC> > 
GC> >   do_once_only skip_comma;
GC> >   for(auto const& s : remaining)
GC> >       {
GC> >       if(!skip_comma)
GC> >           message << ",";
GC> >       message << " '" << s << "'";
GC> >       }
GC> 
GC> As for me, I'd implement this function thus:
GC> 
GC>     std::ostringstream oss;
GC>     oss
GC>         << "Checking columns: "
GC>         << insert_commas_between_elements(quote_elements(remaining))
GC>         << " not found."
GC>         ;
GC> 
GC> avoiding the 'first' and 'only_one' special cases. But of course TIMTOWTDI.

 Having a helper insert_commas_between_elements() or
insert_separator_between_elements() function could be useful too, of
course, but IME such generic do_once_only class can be useful in other,
quite different, situations too. I even thought I saw another loop that had
to do something special (but [not] inserting a separator) in lmi code, but
somehow can't find it right now. Maybe you'll notice it when reviewing the
rest of the changes...

 Regards,
VZ