Re: [Patch] Basic_streambuf::setg() and setp() (2nd take)

[Paolo Carlini <pcarlini at unitus dot it>]

Benjamin Kosnik wrote:

> > Ok?
>
> Yes, this is ok but you need to do sstream and stringbuf::setbuf as well.
>
> Also, 
>
> +	  if (!(this->_M_mode & ios_base::in))
> +	    this->_M_mode = this->_M_mode | ios_base::in;
> +	  if (!(this->_M_mode & ios_base::out))
> +	    this->_M_mode = this->_M_mode | ios_base::out;
>
> can probably just be
>
> +           // So that the replacement buffer can actually be used.
> +	    this->_M_mode =| ios_base::in;
> +	    this->_M_mode =| ios_base::out;
Thanks Benjamin.

However, notice (my third thought, similar to the first one ;)
that this commit would actually _change_ (improve?) the current
behaviour!

In fact, currently we have that, in basic_filebuf::setbuf():

     this->_M_buf = __s;
     this->_M_buf_size = __n;
     _M_set_indeterminate();

but, _M_set_[in]determinate():

     void
     _M_set_determinate(off_type __off)
     {
       const bool __testin = this->_M_mode & ios_base::in;
       const bool __testout = this->_M_mode & ios_base::out;
       if (__testin)
         this->setg(this->_M_buf, this->_M_buf, this->_M_buf + __off);
       if (__testout)
         {
           this->setp(this->_M_buf, this->_M_buf + this->_M_buf_size);
           this->_M_out_lim += __off;
         }
       _M_filepos = this->_M_buf + __off;
     }

therefore, setg and setp are _not_ called _at all_ if __testin
(__testout, respectively) is false!

What do we really want?

Paolo.