[[sub:producer-variants]]
== Producer variants

A producer may want to generate different artifacts for different kinds of consumers: for the same source code, different _binaries_ are produced.
Or, a project may produce artifacts which are for consumption by other projects (same repository) but not for external use.

    def "produces value and stores in backing cache later when not present"() {
        def producer = Mock(Function)
        def completion = Mock(Runnable)

        when:
        def result = cache.get("key", producer, completion)

        then:
        result == "value"

        and:
        1 * target.get("key") >> null
        1 * producer.apply("key") >> "value"
        1 * target.putLater("key", "value", completion)

          "url": "producer-1.0.jar",
          "size": 261,
          "sha1": "29acdaf26447e93ce0c8af7357e6fd4e2d1db71d",
          "md5": "6c53fdd588deb0abfc636c382e25d92e"
        }
      ]
    },
    {
      "name": "mongodbSupportApi",
      "attributes": {
        "org.gradle.usage": "java-api"
      },
      "files": [
        {
          "name": "producer-1.0.jar",

  <!-- that they should prefer consuming it instead. -->
  <!-- do-not-remove: published-with-gradle-metadata -->
  <modelVersion>4.0.0</modelVersion>
  <groupId>org.gradle.demo</groupId>
  <artifactId>producer</artifactId>
  <version>1.0</version>
  <dependencies>
    <dependency>
      <groupId>org.mongodb</groupId>
      <artifactId>mongodb-driver-sync</artifactId>
      <version>3.9.1</version>

/**
 * Represents the details about a particular VCS repository that contains a build that produces zero or more components that can be used during dependency resolution.
 *

     *
     * Production of the value always happens synchronously by the calling thread. However, the implementation may update the backing store with new value synchronously or asynchronously.
     *

            INVOCATION_COUNT.incrementAndGet()
            outputs.file(new File(inputArtifact.get().asFile, SELECTED_PATH))
            outputs.file("produced-file-1.txt").text = "produced1"
            outputs.dir(inputArtifact)
            outputs.file("produced-file-2.txt").text = "produced2"
        }
    }

        logger.quiet(message.get())
    }
}

val producer = tasks.register<Producer>("producer") {
    // Set values for the producer lazily
    // Don't need to update the consumer.inputFile property. This is automatically updated as producer.outputFile changes
    outputFile = layout.buildDirectory.file("file.txt")
}
tasks.register<Consumer>("consumer") {
    // Connect the producer task output to the consumer task input

    }
}

val producer = tasks.register<Producer>("producer")
val consumer = tasks.register<Consumer>("consumer")

consumer {
    // Connect the producer task output to the consumer task input
    // Don't need to add a task dependency to the consumer task. This is automatically added
    inputFile = producer.flatMap { it.outputFile }
}

producer {
    // Set values for the producer lazily

====
include::sample[dir="snippets/dependencyManagement/modelingFeatures-crossProjectPublications-advanced-published/kotlin/producer",files="build.gradle.kts[tags=gradle_metadata_source]"]
include::sample[dir="snippets/dependencyManagement/modelingFeatures-crossProjectPublications-advanced-published/groovy/producer",files="build.gradle[tags=gradle_metadata_source]"]
====

[[sub:gmm-validation]]
== Gradle Module Metadata validation