[slf4j-dev] [JIRA] (SLF4J-371) Support the lambda expression in the Logger

[QOS.CH (JIRA)]

    [ https://jira.qos.ch/browse/SLF4J-371?page=com.atlassian.jira.plugin.system.issuetabpanels:comment-tabpanel&focusedCommentId=19166#comment-19166 ] 

Joachim Durchholz commented on SLF4J-371:
-----------------------------------------

@[~Mezītis] Java cannot use variable names from inside strings for security reasons, so that isn't going to change. However, it does have string interpolation in a more sane format than what String.format() offers:

import static java.text.MessageFormat.format;
...
log.debug(() -> format("Incorrect value: \{0} in column: \{1}", value, column)

> 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}



--
This message was sent by Atlassian JIRA
(v7.3.1#73012)