[jira] [Commented] (LOG4J2-2928) Improve documentation for log methods for messages with parameters

["Ralph Goers (Jira)" <ji...@apache.org>]

    [ https://issues.apache.org/jira/browse/LOG4J2-2928?page=com.atlassian.jira.plugin.system.issuetabpanels:comment-tabpanel&focusedCommentId=17199081#comment-17199081 ] 

Ralph Goers commented on LOG4J2-2928:
-------------------------------------

Documentation improvements are always welcome. An ICLA should not be necessary for a small change like this, but you are always welcome to file one if you believe you will be contributing more things.

> Improve documentation for log methods for messages with parameters
> ------------------------------------------------------------------
>
>                 Key: LOG4J2-2928
>                 URL: https://issues.apache.org/jira/browse/LOG4J2-2928
>             Project: Log4j 2
>          Issue Type: Improvement
>          Components: Documentation
>            Reporter: Marcono1234
>            Priority: Major
>
> The documentation for the {{Logger}} and {{LogBuilder}} methods which create a log message with parameters (e.g. {{Logger.error(message, p1, p2, ...)}}) could probably be improved.
> These methods currently only have their {{message}} method parameter documented as:
> {quote}
> the message to log; the format depends on the message factory.
> {quote}
> However, that is not very helpful because in the most common use case ({{LogManager.getLogger()}}) you are not even dealing with {{MessageFactory}} instances. So it is not clear what a "message factory" is or where to specify one; or even what the default one is.
> I would therefore like to request the following changes:
> # {{Logger}} and {{LogBuilder}} should have a section in their class documentation about messages with parameters, this section should explain:
> #- Default message factory (i.e. used when {{LogManager.getLogger(...)}} method without {{MessageFactory}} is called); link to {{ParameterizedMessageFactory}} (which appears to be the default) and possibly additionally describe directly in {{Logger}} and {{LogManager}} doc its behavior:
> #-- By default {{{}}} is used as placeholder
> #-- Placeholders do not allow any further customization, most importantly they do not support the syntax of JDK's [{{MessageFormat}}|https://docs.oracle.com/en/java/javase/11/docs/api/java.base/java/text/MessageFormat.html] even though it looks similar
> #-- If there are more arguments than placeholders and the last argument is a {{Throwable}} it is logged as such ({{ParameterizedMessageFactory}} doc currently does not mention that either!)
> #-- If there are more arguments than placeholders, those arguments are ignored (unless the last one is a {{Throwable}}, see point above) ({{ParameterizedMessageFactory}} doc currently does not mention that either!)
> #- Link to {{LogManager}} methods allowing providing {{MessageFactory}} and link to {{getFormatterLogger(...)}} methods
> #- Mention that alternatively log methods accepting {{Message}} can be used; link to [manual|https://logging.apache.org/log4j/2.x/manual/messages.html]
> # All {{Logger}} and {{LogBuilder}} methods which create messages with parameters should link to these sections described in point 1 (HTML link)
> # {{LogManager}} methods using the default {{MessageFactory}} should document what the default is
> ----
> Please let me know what you think about this. I will not create a pull request for this if that requires signing the Apache CLA.



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