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https://jira.qos.ch/browse/SLF4J-371?page=com.atlassian.jira.plugin.system.issuetabpanels:comment-tabpanel&focusedCommentId=19453#comment-19453
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Federico Fissore commented on SLF4J-371:
----------------------------------------

An initial effort to support lambdas in slf4j 2.0 has been discussed in the 
mailing list and resulted in this PR [https://github.com/qos-ch/slf4j/pull/203]

If you wish to use the same api with the _current_ version of slf4j, you want 
to take a look at https://github.com/ffissore/slf4j-fluent

> Support the lambda expression in the Logger
> -------------------------------------------
>
>                 Key: SLF4J-371
>                 URL: https://jira.qos.ch/browse/SLF4J-371
>             Project: SLF4J
>          Issue Type: Improvement
>          Components: Core API
>    Affects Versions: 1.7.22
>            Reporter: MiNG
>            Assignee: SLF4J developers list
>
> In some cases, we don't want to calculate the expression for logging eagerly 
> cause the performance reason. Then, we would write the code like the 
> following:
> {code:java}
> if (LOGGER.isWarnEnabled())
> {
>  LOGGER.warn("some message: {}", Json.serialize(obj));
> }{code}
> Before JDK8, there is no way to encapsulate the above code, because the 
> expression is always calculated before passed as an argument. So, many "if"s 
> appear in the code and smell badly.
> Now, the lambda expression is supported by JDK8, the above could be 
> simplified like following:
> {code:java}
> LOGGER.warn(formatter -> formatter.format("some message: {}", 
> Json.serialize(obj)));{code}
> With the default method definition in the org.slf4j.Logger:
> {code:java}
> public interface Logger
> {
>  default void warn(Function<MessageFormatter, String> messageSupplier)
>  {
>   if (this.isWarnEnabled())
>   {
>    /* Calculate the expression only if the WARN level logging is enabled. */
>    this.warn(messageSupplier.apply(this.getFormatter()));
>   }
>  }
> }{code}



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