Re: [boost] Custom logging backend difficulty

Subject: Re: [boost] Custom logging backend difficulty
From: Kenneth Adam Miller (kennethadammiller_at_[hidden])
Date: 2014-10-27 15:03:43

Ah ok that clarifies somewhat;  I thought it was the formatter that I was
having trouble with. I tried setting one, and then saw that the text was
added to the console to test. But I'm doing
boost::log::add_common_attributes(), and I print the string to std out just
to make sure that I will get what I expect. As it turns out, I think that
the backend is supposed to visit the record_view, and the record view has
the default attributes and any others added.

I'm trying to get those extra attributes; if I do BOOST_LOG(lg) << " blah"
<< endl; I get "blah" on my screen which I swap out the backend from the
default. My backend just prints to the console.

How do I had the record_view items to the string to be sent?

On Mon, Oct 27, 2014 at 2:56 PM, Andrey Semashev <andrey.semashev_at_[hidden]>
wrote:

> On Monday 27 October 2014 14:40:22 Kenneth Adam Miller wrote:
> > So, I need malleable logging facilities, and so far I've identified
> boost's
> > logging facilities as useful. I've read the docs on logging, and right
> now
> > I'm having difficulty achieving what I want-basically, I have a custom
> > backend, in order that when logging is done, it gets routed to an
> > alternative destination - over the network namely.
> >
> > I extended from text_ostream_backend, and basically I'm having the
> > following trouble:
> >
> > I don't understand the record_view visitation API. I'd like the ability
> to
> > set formatters and what not to remain untouched, but have the final
> > formatted result sent off else where. I can change this by sending the
> > string received in the consume function that has to be overrode, but the
> > values are lost in the record_view.
> >
> > void consume (const record_view & rec, std::string s);
> >
> > where I do  { send(s); } for the body.
> >
> >
> > What I think is necessary is just to retain the default behavior of
> > accepting whatever formatter was specified...
> >
> > What is the best way to go about achieving what I want?
>
> I'm sorry, I don't understand what you mean.
>
> The first argument of consume() is the record view, which contains all
> attribute values that were passed to the library when the log record was
> created. This includes the message text. Whether or not you apply a
> formatter
> to it, the view remains intact and can be used in your sink backend if
> needed.
> Accessing attribute values is summarized here:
>
>
> http://www.boost.org/doc/libs/1_56_0/libs/log/doc/html/log/detailed.html#log.detailed.core.record
>
> The second argument is the result of formatting, i.e. the format of the
> string
> is defined by the formatter. If you send log records as strings over the
> network then this string is probably what you need, provided that you set
> the
> appropriate formatter.
>
>
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