* HACKING: update instructions

HACKING

@@ -7,6 +7,7 @@ some of the more stylistic-aesthetic rules are clearly visible in current
 source code, so as long as any new code 'fits in', it should go a long way in
 satisfying these rules. 
 
+
 ** Coding style
 
    For consistency and even more important, to keep things understandable, mu
@@ -45,6 +46,26 @@ satisfying these rules.
    11. returned strings of type char* must be freed by the caller; if they are
        not to be freed, 'const char*' should be used instead
 
+** Logging
+   
+   For logging, mu uses the GLib logging functions/macros as listed below,
+   except when logging may not have been initialized.
+
+   The logging system redirects most logging to the log file (typically,
+   ~/.mu/mu.log). g_warning, g_message and g_critical are shown to the user,
+   except when running with --quiet, in which case g_message is *not* shown.
+
+   =g_message= are for non-error messages the user will see (unless running with --quiet)
+   =g_warning= is for problems the user may be able to do something about (and
+   they are written on stderr)
+   =g_critical= is for serious, internal problems (g_return_if_fail and
+   friends use this). (and they are written on stderr)
+
+   don't use g_error
+
+   if you just want to log something in the log file, use MU_LOG_WRITE, as
+   defined in mu-util.h
+
 
 #+ Local Variables: ***
 #+ mode:org ***