Gradle Incremental Builds - Declaring Inputs and Outputs with Runtime API

External

• https://docs.gradle.org/current/userguide/more_about_tasks.html#sec:task_input_output_runtime_api

Internal

• Gradle Incremental Builds

Overview

Annotations in custom task types are the cleanest way to declare inputs and outputs. However, simple tasks can be configured to participate in incremental builds by using the Runtime API. There is also the case of the enhanced tasks we don't have source code for. In all these situations, we can configure the task's inputs and outputs with an alternative runtime API:

Task.getInputs()
Task.getOutputs()
Task.getDestroyables()

The methods return TaskInputs, TaskOutputs and TaskDestroyables instances. These objects have methods that allow specifying files, directories and values. The API is almost at parity with the annotations, it is only missing @Nested.

Example

task inLineTask {

  inputs.property("engine", TemplateEngineType.FREEMARKER)
  inputs.files(fileTree("src/templates"))
    .withPropertyName("sourceFiles")
    .withPathSensitivity(PathSensitivity.RELATIVE) 
  inputs.property("templateData.name", "docs")
  inputs.property("templateData.variables", [year: 2020]) 
  outputs.dir("$buildDir/genOutput2")
    .withPropertyName("outputDir")

  doLast {
    // Process the templates here
  } 
}