I see { } are used for closures, and then I believe when a $ is put in front of braces, it is simply doing a variable substitution within a string. I can't find the documentation on how the $ works in the reference ... hard to search on it unfortunately, and the Groovy String documentation is lacking in introducing this. Can you please point me to the documentation and/or explain the "$" operator in Groovy -- how all it can be used? Does Grails extend it at all beyond Groovy?
4 Answers
In a GString (groovy string), any valid Groovy expression can be enclosed in the ${...} including method calls etc.
This is detailed in the following page.
3Grails does not extend the usage of $ beyond Groovy. Here are two practical usages of $
String Interpolation
Within a GString you can use $ without {} to evaluate a property path, e.g.
def date = new Date()
println "The time is $date.time"If you want to evaluate an expression which is more complex than a property path, you must use ${}, e.g.
println "The time is ${new Date().getTime()}"Dynamic Code Execution
Dynamically accessing a property
def prop = "time"
new Date()."$prop"Dynamically invoking a method
def prop = "toString"
new Date()."$prop"()As pointed out in the comments this is really just a special case of string interpolation, because the following is also valid
new Date().'toString'()$ is not an operator in Groovy. In string substitution it identifies variables within the string - there's no magic there. It's a common format used for inline variables in many template and programming languages.
All special Groovy operators are listed here:
Work in side Jenkins File in pipeline
#!/usr/bin/env groovy
node{ stage ('print'){ def DestPath="D\$\\" println("DestPath:${DestPath}") }
}
