**FastAPI** has a very powerful but intuitive **<abbr title="also known as components, resources, providers, services, injectables">Dependency Injection</abbr>** system.

It is designed to be very simple to use, and to make it very easy for any developer to integrate other components with **FastAPI**.

## What is "Dependency Injection"

The main drawback of this method is that it is ordering dependent.
Keeping order in a very large graph can be a challenge.
For example, what if the new version of a dependency ends up having its own dependency declarations in a different order than the previous version?

With Maven, this could have unwanted impact on resolved versions.
--

.An explicit configuration dependency
====
include::sample[dir="snippets/dependencyManagement/modelingFeatures-crossProjectPublications-simple/kotlin",files="consumer/build.gradle.kts[tags=explicit-configuration-dependency]"]
include::sample[dir="snippets/dependencyManagement/modelingFeatures-crossProjectPublications-simple/groovy",files="consumer/build.gradle[tags=explicit-configuration-dependency]"]
====

[[sec:cpp_library_task_variants]]
=== Variant-dependent Tasks

The {cpp} Library Plugin creates tasks based on variants of the library component.
Read the <<building_cpp_projects.adoc#sec:introducing_build_variants-cpp,introduction to build variants>> for more information.
The following diagrams show the relationship between variant-dependent tasks.

.{cpp} Library Plugin variant-dependent task graph
image::cpp-library-variant-task-graph.png[]

.Declaring a Scala 3 dependency for production code
====
include::sample[dir="snippets/scala/scala3/kotlin",files="build.gradle.kts"]
include::sample[dir="snippets/scala/scala3/groovy",files="build.gradle"]
====

If Scala is only used for test code, the `scala-library` dependency should be added to the `testImplementation` configuration:

	// These are keyed by the internal uid() function on collections.
	// Note this does not include `parent`, which is the *primary* dependency declared outside of transformation functions.
	collectionDependencies sets.Set[collectionUID]
	// Stores a map of I -> secondary dependencies (added via Fetch)
	objectDependencies map[Key[I]][]*dependency

	// eventHandlers is a list of event handlers registered for the collection. On any changes, each will be notified.

Explicit dependencies :: These dependencies are explicitly declared in the build script using the `dependsOn`, `mustRunAfter`, or `shouldRunAfter` methods. For example, if you want to ensure that `taskB` always runs after `taskA`, you can explicitly declare this dependency using `taskB.mustRunAfter(taskA)`.

 *
 *     //default settings for downloading sources and Javadoc:
 *     downloadSources = true
 *     downloadJavadoc = false
 *
 *     //if you want to expose test classes to dependent projects
 *     containsTestFixtures = true
 *
 *     //customizing which Eclipse source directories should be marked as test
 *     testSourceSets = [sourceSets.test]
 *

[[implicit_dependency]]
== Implicit dependencies between tasks

This error indicates that you have a task which depends on another, but that no explicit or implicit dependency is declared between those two tasks.
As a consequence, the results of the build are dependent on the order of execution of tasks, often referred to "accidental dependencies between tasks".

     *
     * @param dependency dependency for which to get the coordinate
     * @return coordinate for the given dependency
     *
     * @see DependencyCoordinateFactory#create(Session, Dependency)
     */
    @Nonnull
    DependencyCoordinate createDependencyCoordinate(@Nonnull Dependency dependency);

    /**