Implement pre-spawn API to allow modifications to spawned entities.

See preceding commit for why this change was included.

2 files changed, 36 insertions, 0 deletions

diff --git a/src/main/java/org/bukkit/World.java b/src/main/java/org/bukkit/World.java
index 02cad41c..f34b3a93 100644
--- a/src/main/java/org/bukkit/World.java
+++ b/src/main/java/org/bukkit/World.java
@@ -16,6 +16,7 @@ import org.bukkit.inventory.ItemStack;
 import org.bukkit.material.MaterialData;
 import org.bukkit.metadata.Metadatable;
 import org.bukkit.plugin.messaging.PluginMessageRecipient;
+import org.bukkit.util.Consumer;
 import org.bukkit.util.Vector;
 
 /**
@@ -702,6 +703,24 @@ public interface World extends PluginMessageRecipient, Metadatable {
     public <T extends Entity> T spawn(Location location, Class<T> clazz) throws IllegalArgumentException;
 
     /**
+     * Spawn an entity of a specific class at the given {@link Location}, with
+     * the supplied function run before the entity is added to the world.
+     * <br>
+     * Note that when the function is run, the entity will not be actually in
+     * the world. Any operation involving such as teleporting the entity is undefined
+     * until after this function returns.
+     *
+     * @param location the {@link Location} to spawn the entity at
+     * @param clazz the class of the {@link Entity} to spawn
+     * @param function the function to be run before the entity is spawned.
+     * @param <T> the class of the {@link Entity} to spawn
+     * @return an instance of the spawned {@link Entity}
+     * @throws IllegalArgumentException if either parameter is null or the
+     *     {@link Entity} requested cannot be spawned
+     */
+    public <T extends Entity> T spawn(Location location, Class<T> clazz, Consumer<T> function) throws IllegalArgumentException;
+
+    /**
      * Spawn a {@link FallingBlock} entity at the given {@link Location} of
      * the specified {@link Material}. The material dictates what is falling.
      * When the FallingBlock hits the ground, it will place that block.
diff --git a/src/main/java/org/bukkit/util/Consumer.java b/src/main/java/org/bukkit/util/Consumer.java
new file mode 100644
index 00000000..fb9e6b90
--- /dev/null
+++ b/src/main/java/org/bukkit/util/Consumer.java
@@ -0,0 +1,17 @@
+package org.bukkit.util;
+
+/**
+ * Represents an operation that accepts a single input argument and returns no
+ * result.
+ *
+ * @param <T> the type of the input to the operation
+ */
+public interface Consumer<T> {
+
+    /**
+     * Performs this operation on the given argument.
+     *
+     * @param t the input argument
+     */
+    void accept(T t);
+}