diff options
Diffstat (limited to 'lib/kernel/doc/src/logger_chapter.xml')
| -rw-r--r-- | lib/kernel/doc/src/logger_chapter.xml | 18 |
1 files changed, 17 insertions, 1 deletions
diff --git a/lib/kernel/doc/src/logger_chapter.xml b/lib/kernel/doc/src/logger_chapter.xml index 23a289f2ee..dc68d5c761 100644 --- a/lib/kernel/doc/src/logger_chapter.xml +++ b/lib/kernel/doc/src/logger_chapter.xml @@ -194,10 +194,26 @@ the log event's <seealso marker="#metadata">metadata</seealso>. The report callback is a convenience function that the <seealso marker="#formatters">formatter</seealso> can use - to convert the report to a format string and arguments. The + to convert the report to a format string and arguments, or + directly to a string. The formatter can also use its own conversion function, if no callback is provided, or if a customized formatting is desired.</p> + <p>The report callback must be a fun with one or two + arguments. If it takes one argument, this is the report + itself, and the fun returns a format string and arguments:</p> + <pre>fun((<seealso marker="logger#type-report"><c>logger:report()</c></seealso>) -> {<seealso marker="stdlib:io#type-format"><c>io:format()</c></seealso>,[term()]})</pre> + <p>If it takes two arguments, the first is the report, and the + second is a map containing extra data that allows direct + coversion to a string:</p> + <pre>fun((<seealso marker="logger#type-report"><c>logger:report()</c></seealso>,<seealso marker="logger#type-report_cb_config"><c>logger:report_cb_config()</c></seealso>) -> <seealso marker="stdlib:unicode#type-chardata"><c>unicode:chardata()</c></seealso>) + </pre> + <p>The fun must obey the <c>encoding</c>, <c>depth</c> + and <c>chars_limit</c> parameters provided in the second + argument, as the formatter can not do anything useful of these + parameters with the returned string. This variant is used when + the formatting of the report depends on the size and encoding + parameters.</p> <p>Example, format string and arguments:</p> <code>logger:error("The file does not exist: ~ts",[Filename])</code> <p>Example, string:</p> |