Re: [boost] streams - basic_nullbuf

From: John Torjo (john.lists_at_[hidden])
Date: 2003-10-10 01:02:38

Hi,

I came a little late - sorry about that.

Anyway, I have a more thorough implementation of nullstream,
since there are more details that could be taken into considerance.

I've attached the code - if anyone is interested, I can comment on them
a little.

The idea is that you might need to sometimes pass nullstream to a function
taking an ostream& reference.

At this point you have two options:
- ignoreoutput (which silently ignores output)
- failbit - which is much faster than ignoreoutput, since it sets the
  std::ios::failbit on the stream. Internally, when something is written to
the stream,
  first a check is performed to see if the stream is in good state. If it's
not, the
  function ends right there.

Best,
John

----- Original Message -----
From: "Jeff Garland" <jeff_at_[hidden]>
To: "Boost mailing list" <boost_at_[hidden]>
Sent: Thursday, September 25, 2003 2:24 PM
Subject: Re: [boost] streams - basic_nullbuf

> On Thu, 25 Sep 2003 Lars Gullik Bjønnes wrote
>
> > Jeff Garland wrote:
> > > My approach was a bit different in that I didn't bother with the
buffer at
> > > all, but created the ostream interface directly in hope that the
>
> >But if you are going to compile anyway, then you could use other
> >methods as well (pre-processor).
>
> Yes, but macros are evil and impact code readability.  I just really hate
lots
> of code like:
>
>   TRACE("I'm here" << foo << std::endl);
>
> The all caps thing is really bothersome to me.  And of course there is the
> loss of ability to set have a tracing version and a non-tracing version in
one
>  compilation unit.
>
> > How will this behave for user defined types?
>
> Same because of omitted detail below...
>
> > Do I have to add a operator<< for both ostream and null_ostream?
>
> No...
>
> template<class T>
> null_ostream&
> operator<<(null_ostream& os, const T&)
> {
>   return os;
> }
>
> I'm not saying my idea was fully baked -- there may be some fatal flaw I
> haven't worked out.  Just wanted to point out other potential approaches
and
> requirements while expressing support for getting something like this in
boost.
>
> Jeff
>
>
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