[jira] [Comment Edited] (LOG4J2-599) Support lambda functions (or similar) for log message parameters

["Mikael Ståldal (JIRA)" <ji...@apache.org>]

    [ https://issues.apache.org/jira/browse/LOG4J2-599?page=com.atlassian.jira.plugin.system.issuetabpanels:comment-tabpanel&focusedCommentId=14658274#comment-14658274 ] 

Mikael Ståldal edited comment on LOG4J2-599 at 8/5/15 2:24 PM:
---------------------------------------------------------------

For Scala, the preferred approach to achieve this is to use string interpolation and macros.

That has already been done for SLF4J: https://github.com/typesafehub/scala-logging
and it would be easy to do the same for Log4j 2.


was (Author: mikaelstaldal):
For Scala, the preferred approach to achieve this is to use macros: https://github.com/typesafehub/scala-logging

> Support lambda functions (or similar) for log message parameters
> ----------------------------------------------------------------
>
>                 Key: LOG4J2-599
>                 URL: https://issues.apache.org/jira/browse/LOG4J2-599
>             Project: Log4j 2
>          Issue Type: Brainstorming
>          Components: Core
>            Reporter: Matt Sicker
>            Priority: Minor
>              Labels: Java8
>
> It would be nice if we could support 0-param lambda functions (or the equivalent: interfaces with a single empty-parameter message call), or more simply, allow Runnables (or something similar) to be passed which will be dynamically executed if the log message is enabled.
> The use case here is that although string construction of the log message is a performance issue that is already solved quite well, the problem of adding in information to the log message that makes other calculations still needs to be wrapped in an if check.
> I'm not sure if it'd be best to just use Runnable, or create a new interface, or try to emulate how Java 1.8 lambdas work via an interface with a single method defined. The details here would still need to be fleshed out, but I think this sort of feature could be rather handy (especially in a Java 1.8+ environment, or in Groovy/Scala/etc.).



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