@erichelgeson @james.kleeh my thinking is this in java, it is bad practice to do this:

String value = "..."
<http://log.info|log.info>("Hello " + value);

That's because the string manipulation (i.e. in this case, string concatenation) can substantially reduce performance. And the best practice for this one before (i.e. pre-slf4j) was to do the following

String value = "..."
if (log.isInfoEnabled()) {
    <http://log.info|log.info>("Hello " + value);
}

This then added a lot of clutter in java codes pre-slf4j days. And then slf4j came and then introduced their placeholders.

String value = "..."
<http://log.info|log.info>("Hello {}", value);

Which meant, "{}" will not be replaced by

value

not unless

log.isInfoEnabled()

evaluates to

true

(Note:

log.isInfoEnabled()

is invoked inside slf4j's

<http://log.info|log.info>()

) Now going to groovy, if we have this

<http://log.info|log.info>("Hello ${value}")

Then we go back to the original issue which slf4j tries to prevent in the first place - string manipulation without checking log level. So to fix this, we can change this to

<http://log.info|log.info>('Hello {}', value)

This then avoids the unnecessary GString manipulation if

isInfoEnabled()

is

false

Did I get that right or is there some sort of special compiler optimisation that automagically handles this? 🙂