Multi-Method Library Steps¶

Typically, Library Steps define a call() method that allows the step to be invoked via its name (such as build()).

This isn't required. Groovy's Call Operator¹ means that invoking build() functionally equivalent to invoking build.call().

Steps, therefore, can define alternative methods beyond just the call() method.

Use Case: Utility Steps¶

Multi-Method Library Steps are most useful when creating Library Steps that wrap a particular utility. The methods on the step can then represent different actions the utility can take.

Utility Step Example: Git

Git Utility StepUsage

git.groovy

void add(String files){
  sh "git add ${files}"
}

void commit(String message){
  sh "git commit -m ${message}"
}

void push(){
  sh "git push" 
}

Jenkinsfile

node{
  checkout scm
  writeFile file: 'test.txt', text: 'hello, world'
  git.add('test.txt')
  git.commit('add test file')
  git.push()
}

Groovy Command Chain¶

Expressive DSLs can be created when coupling multi-method steps with Groovy's Command Chain feature.

Using Command Chains With The Git Utility

Command Chains could be used to improve upon the previous example.

Without Command ChainsWith Command Chains

Jenkinsfile

node{
  checkout scm
  writeFile file: 'test.txt', text: 'hello, world'
  git.add('test.txt')
  git.commit('add test file')
  git.push()
}

Jenkinsfile

node{
  checkout scm
  writeFile file: 'test.txt', text: 'hello, world'
  git add 'test.txt'
  git commit 'add test file'
  git.push()
}

Groovy Call Operator ↩