Dependency Management

Dependencies are common. You need to hook into another plugin. You don't want to write the same code someone else has already solved. Whatever you do, you need a way to manage your dependencies effectively.

Plugin dependencies

Adding a dependency on another plugin is done with the @Plugin annotation in your main class. Let's revisit that briefly:

@Plugin(
  id = "myfirstplugin",
  name = "My Plugin",
  version = "0.1.0"
)
public class VelocityTest {
  // ...
}

Say we have a dependency on another plugin, call it wonderplugin. To add it as a dependency, do the following:

@Plugin(
  id = "myfirstplugin",
  name = "My Plugin",
  version = "0.1.0",
  dependencies = {
    @Dependency(id = "wonderplugin")
  }
)
public class VelocityTest {
  // ...
}

The id of the dependency is the same as the other plugin's id from its @Plugin annotation. This is why having a stable plugin ID is important.

That's it! Now, your plugin will require wonderplugin to load, and when it does, it will load after wonderplugin.

To specify multiple dependencies, separate them by commas: dependencies = {@Dependency(id = "wonderplugin"), @Dependency(id = "otherplugin")}

Optional plugin dependencies

To make a dependency optional, add optional = true, like shown:

@Plugin(
  id = "myfirstplugin",
  name = "My Plugin",
  version = "0.1.0",
  dependencies = {
    @Dependency(id = "wonderplugin", optional = true)
  }
)
public class VelocityTest {
  // ...
}

External dependencies

caution

Please remember to relocate any dependencies you shade. Failure to relocate will lead to dependency conflicts with other plugins.

Dependencies on other libraries aren't handled by Velocity. You will need to add them using your build system.

If your plugin does not shade its dependencies, but rather attaches them from a directory, you may use the PluginManager's addToClasspath method instead of using reflection to access the ClassLoader.