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{{merge|SG_LOG()}}
<code>SG_LOG</code> is a wrapper macro for the [[SimGear]] <code>logstream</code> class.  By default, the <code>logstream</code> class writes all output to the [[console]].  <code>SG_LOG</code> simplifies debugging for core developers who regularly [[Building FlightGear|compile from source]].  It allows you to easily associate your debug messages with a "channel" and with a "priority". This mechanism allows users to explicitly enable to certain log messages, while ignoring others. This can be helpful in order to troubleshoot certain problems.


<code>SG_LOG</code> is a wrapper macro for the [[SimGear]] <code>logstream</code> class.  By default, the <code>logstream</code> class writes all output to the console.  <code>SG_LOG</code> simplifies debugging for core developers who regularly [[Building FlightGear|compile from source]].  It allows you to easily associate your debug messages with a "channel" and with a "priority". This mechanism allows users to explicitly enable to certain log messages, while ignoring others. This can be helpful in order to troubleshoot certain problems.
== Usage ==
Logging settings can be modified using the <code>--log-level=[level]</code> and <code>--log-class=[class]</code> [[command line]] options. Where <code>level</code> is one of the following:
* <code>bulk</code>
* <code>debug</code>
* <code>info</code>
* <code>warn</code>
* <code>alert</code>
* <code>popup</code>
And <code>class</code> is a white space seperated list of any (combination) of the following:
* <code>all</code>
* <code>ai</code>
* <code>enviroment</code>
* <code>flight</code>
* etc.


Logging settings can be modified using the <code>--log-level=[level]</code> [[command line]] option, detailed help about most available command line options can be obtained from the fgfs executable by calling it with the following arguments: <code>--help --verbose</code>.
For a complete list of available classes, see {{simgear file|simgear/debug/debug_types.h}}.


If you are interested in simply logging certain properties to a file at runtime, you can use either FlightGear's built-in logging framework, or the [[generic protocol]].  See [[Logging properties]] and [[Generic protocol]] for more details.
If you are interested in simply logging certain properties to a file at runtime, you can use either FlightGear's built-in [[Logging properties|logging framework]], or the [[generic protocol]].


{{FGCquote
== Related content ==
  |The standard mechanism for making FlightGear "log" stuff to the console (or log file) is using the SG_LOG() macro
=== Wiki articles ===
  |{{cite web |url=http://forum.flightgear.org/viewtopic.php?p=233211#p233211
* [[Command line options#Debugging Options]]
    |title=<nowiki>Re: 3.4 and the pain begins ...</nowiki>
* [[Commonly used debugging tools#Console and startup log output]]
    |author=<nowiki>Hooray</nowiki>
    |date=<nowiki>Thu Feb 26</nowiki>
  }}
}}


== Development ==
=== Source code ===
{{FGCquote
* {{simgear file|simgear/debug/logstream.cxx}}
  |'m working a bit on reworking the logging exposed to Nasal, since it hasn't been updated in years (besides the addition of the never-used logprint() by James, the old printlog() only goes to the $FG_HOME/fgfs.log file if it would also go to the console and is implemented in globals.nas - aka can't be depended on in $FG_ROOT/Nasal/*.nas). This is going to eventually help with the Nasal REPL (aka to capture output), but I discovered something really weird: sglog().would_log() returns true for any priority &gt;{{=}} INFO! This almost seems like a bug to me, but OTOH it is required by the SG_LOG() macro to ensure that the logging file is not ignored in the if statement (since SG_LOG() uses would_log()).
* {{simgear file|simgear/debug/logstream.hxx}}
  |{{cite web |url=http://forum.flightgear.org/viewtopic.php?p=202850#p202850
* {{simgear file|simgear/debug/debug_types.h}}
    |title=<nowiki>sglog().would_log()</nowiki>
    |author=<nowiki>Philosopher</nowiki>
    |date=<nowiki>Fri Mar 07</nowiki>
  }}
}}
 
== External links ==
* {{repo link|site=gito|proj=fg/simgear|path=simgear/debug/logstream.cxx}}
* {{repo link|site=gito|proj=fg/simgear|path=simgear/debug/logstream.hxx}}
* {{repo link|site=gito|proj=fg/simgear|path=simgear/debug/debug_types.h}}


[[Category:Core developer documentation]]
[[Category:Core developer documentation]]

Revision as of 08:33, 27 September 2020

SG_LOG is a wrapper macro for the SimGear logstream class. By default, the logstream class writes all output to the console. SG_LOG simplifies debugging for core developers who regularly compile from source. It allows you to easily associate your debug messages with a "channel" and with a "priority". This mechanism allows users to explicitly enable to certain log messages, while ignoring others. This can be helpful in order to troubleshoot certain problems.

Usage

Logging settings can be modified using the --log-level=[level] and --log-class=[class] command line options. Where level is one of the following:

  • bulk
  • debug
  • info
  • warn
  • alert
  • popup

And class is a white space seperated list of any (combination) of the following:

  • all
  • ai
  • enviroment
  • flight
  • etc.

For a complete list of available classes, see simgear/simgear/debug/debug_types.h.

If you are interested in simply logging certain properties to a file at runtime, you can use either FlightGear's built-in logging framework, or the generic protocol.

Related content

Wiki articles

Source code

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