From dfb9147fc91d6a8b565a4f4075b6624b9870b315 Mon Sep 17 00:00:00 2001
From: Johnathan Gilday <me@johnathangilday.com>
Date: Fri, 20 Dec 2019 09:50:52 -0500
Subject: [PATCH] :construction: Gradle 6 - Task Configuration Avoidance

---
 .../configuration-avoidance/build.gradle.kts  | 37 +++++++++++++++++++
 gradle-6/gradle.properties                    |  1 +
 gradle-6/settings.gradle.kts                  |  1 +
 3 files changed, 39 insertions(+)
 create mode 100644 gradle-6/configuration-avoidance/build.gradle.kts

diff --git a/gradle-6/configuration-avoidance/build.gradle.kts b/gradle-6/configuration-avoidance/build.gradle.kts
new file mode 100644
index 0000000000..e84f08bf93
--- /dev/null
+++ b/gradle-6/configuration-avoidance/build.gradle.kts
@@ -0,0 +1,37 @@
+plugins {
+    base
+}
+
+description = """
+    Demonstrates Gradle Configuraiton Avoidance API. Creates a new configuration "extralibs" to 
+    which we add dependencies. The custom task "copyExtraLibs" copies those dependencies to a new 
+    build directory "extra-libs". This build uses the Task Configuraion Avoidance APIs which have 
+    been marked stable in Gradle 6.0
+""".trimIndent()
+
+// extraLibs is a NamedDomainObjectProvider<Configuration!> - the Configuration object will not be
+// realized until it is needed. In the meantime, the build may reference it by name
+val extralibs by configurations.registering
+
+dependencies {
+    // we can call extralibs.name without causing the extralibs to be realized
+    add(extralibs.name, "junit:junit:4.12")
+}
+
+// extraLibsDir is a Provider<Directory!> - the Directory object will not be realized until it is
+// needed
+val extraLibsDir = project.layout.buildDirectory.dir("extra-libs")
+
+// copyExtraLibs is a TaskProvider<Copy!> - the task will not be realized until it is needed
+val copyExtraLibs by tasks.registering(Copy::class) {
+    // the copy task's "from" and "into" APIs accept Provider types to support configuration
+    // avoidance
+    from(extralibs)
+    into(extraLibsDir)
+}
+
+// configures the "build" task only if it needs to be
+tasks.build {
+    // dependsOn accepts a TaskProvider to avoid realizing the copyExtraLibs needlessly
+    dependsOn(copyExtraLibs)
+}
diff --git a/gradle-6/gradle.properties b/gradle-6/gradle.properties
index f97ebb7d33..7da8b3d72a 100644
--- a/gradle-6/gradle.properties
+++ b/gradle-6/gradle.properties
@@ -1 +1,2 @@
 org.gradle.parallel=true
+org.gradle.configureondemand=true
diff --git a/gradle-6/settings.gradle.kts b/gradle-6/settings.gradle.kts
index babe431175..88cf74c4d7 100644
--- a/gradle-6/settings.gradle.kts
+++ b/gradle-6/settings.gradle.kts
@@ -1,5 +1,6 @@
 rootProject.name = "gradle-6"
 
+include("configuration-avoidance")
 include("dependency-constraints")
 include("fibonacci-spi")
 include("fibonacci-recursive")