Jenkins Shared Library Recursive Function Calls

Question

I have declarative pipeline and uses jenkins shared library. I am trying to make recursive function call within jenkins shared library.

My shared lib structure is something similar to below:

vars/xyz.groovy

Inside xyz.groovy I have method foo, to whom I call xyz.foo from my pipeline which works. However recursive call from

foo(){
foo()   // says No such DSL method
xyz.foo() //says no signature of method: java.lang.class.foo
}

I am trying to understand how to calls functions within jenkins shared library.

Answer 1

this.methodName is rightway to call function recursively inside shared library. All though method is not a part of class. But using this.foo() worked for me.

Answer 2

I was trying something similar to invoke a recursive function with a method declared in the same file.groovy At the end, the option @Sagar gave didn't work for me As a workaround, I created the recursive function in a new file (b.groovy) and invoke it from the original file (a.groovy). it worked like a charm:)

example.

b.groovy

/**
 * recursive function to compare semantic version form package.json and tag version, only evaluate x.x.x version
 * 0 same version
 * 1 package.json version is GREATER than repo tag version
 * -1 package.json version is SMALLER than repo tag version
 */
int call(ArrayList versionPackageJsonSplit, ArrayList versionTagRepoSplit, Integer iteration) {
    if (versionPackageJsonSplit[iteration].toInteger() == versionTagRepoSplit[iteration].toInteger()) {
        if (iteration == 2) {
            println 'return 0'
            return 0
        }
        return utility_cdkCompareVersions (versionPackageJsonSplit, versionTagRepoSplit, iteration+1) // --> recursive invocation
    } else if (versionPackageJsonSplit[iteration].toInteger() > versionTagRepoSplit[iteration].toInteger()) {
        println 'return 1'
        return 1
    } else if (versionPackageJsonSplit[iteration].toInteger() < versionTagRepoSplit[iteration].toInteger()) {
        println 'return -1'
        return -1
    }
}

a.groovy

.
.
.

compareVersionsResult = b (versionPackageJsonSplit, versionTagRepoSplit, 0)
println compareVersionsResult
.
.
.
.


```

Answer 3

So far the least awful way I've found to do this reliably is to create a top-level wrapper method with a recursive closure inside it:

def recursiveMethod(args) {
  Closure rec
  rec = { arg ->
    if (recursiveCase) {
      return rec(…)
    }
    else {
      return baseCase
    }
  }

  return rec(…)
}

The upside is that you can reference method args or method-scoped state variables from within the closure without having to pass them around the recursive stack, so recursive calls may look a little cleaner. The downside is a little extra boilerplate to do the wrapping, and also that the closure args have to be named differently than the method args or Groovy raises an error.