Differences

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--- tutorial:mixin_injects [2020/05/28 18:28] – b0undarybreaker
+++ tutorial:mixin_injects [2022/08/05 19:19] (current) – Added signed to integer types clomclem
@@ Line 2: / Line 2: @@
 ===== Introduction =====
-Injects allows you to place custom code at a specified position inside an existing method. For a working example, view the [[https://fabricmc.net/wiki/tutorial:mixin_injects#practical_example|Practical Example]] category at the bottom of this page. The standard form of an inject is as shown:
+Injects allows you to place custom code at a specified position inside an existing method. For a working example, view the [[tutorial:mixin_injects#practical_example|Practical Example]] category at the bottom of this page. The standard form of an inject is as shown:
 <code java>
-@Inject(method = "", at = @At("INJECTION POINT REFERENCE"))
+@Inject(method = "METHOD NAME OR SIGNATURE", at = @At("INJECTION POINT REFERENCE"))
 private void injectMethod(METHOD ARGS, CallbackInfo info) {
@@ Line 28: / Line 28: @@
 | D | double | double-precision floating-point value |
 | F | float | single-precision floating-point value |
-| I | int | integer |
+| I | int | signed integer |
-| J | long | long integer |
+| J | long | signed long integer |
 | L//ClassName//; | reference | an instance of //ClassName// |
 | S | short | signed short |
 | Z | boolean | ''true'' or ''false'' |
-| [FieldType | reference | one array dimension |
+| [ | reference | one array dimension |
-A method descriptor is comprised of the method name, followed by a set of parentheses containing the input types, followed by the output type. A method defined in Java as ''Object m(int i, double d, Thread t)'' would have the method descriptor ''m(IDLjava/lang/Thread;)Ljava/lang/Object;''.
+A method descriptor is comprised of the method name, followed by a set of parentheses containing the parameter types, followed by the return type. A method defined in Java as ''Object m(int i, double[] d, Thread t)'' would have the method descriptor ''m(I[DLjava/lang/Thread;)Ljava/lang/Object;''.
-//@Inject// methods always have a void return type. The method name does not matter; using something that describes what the inject does is best. The target method's arguments are placed first in the method's header, followed by a ''CallbackInfo'' object. If the target method has a return type (T), ''CallbackInfoReturnable<T>'' is used instead of ''CallbackInfo''.
+In the case that the return type is void, you need to use V (Void Descriptor Type) as the type (for example, ''void foo(String bar)'' would become ''foo(Ljava/lang/String;)V'').
+Generics' types are left out, as generics don't exist on runtime. So ''Pair<Integer, ? extends Task<? super VillagerEntity>‍>'' would become ''Lcom/mojang/datafixers/util/Pair''.
+''@Inject'' methods always have a void return type. The method name does not matter and neither does the access modifier; using something that describes what the inject does is best. The target method's arguments are placed first in the method's header, followed by a ''CallbackInfo'' object. If the target method has a return type (T), ''CallbackInfoReturnable<T>'' is used instead of ''CallbackInfo''.
 === Returning & Cancelling from Inject ===
@@ Line 47: / Line 51: @@
 === Injecting into Constructors ===
-To inject into a constructor, use ''<init>()V'' as the method target, with ''()'' containing the constructor argument descriptors. When injecting into constructors, ''@At'' must be set to either ''TAIL'' or ''RETURN''.
+To inject into a constructor, use ''<init>()V'' as the method target, with ''()'' containing the constructor argument descriptors. When injecting into constructors, ''@At'' must be set to either ''TAIL'' or ''RETURN''. No other forms of injection are officially supported. Note that some classes have methods named ''init'' which are different from ''<init>''. Don't get confused!
+To inject into a static constructor, use ''<clinit>'' as the method name.
 ===== Practical Example =====
-The following example injects a print statement at the top of ''TitleScreen#init''.
+The following example injects a print statement at the top of ''TitleScreen#init'' (note: the method ''init'' is a normal method and not a constructor).
 <code java [enable_line_numbers="false"]>
@@ Line 62: / Line 68: @@
 </code>
-For more information on this particular example, view its usage in the [[Fabric Example Mod repo]].
+For more information on this particular example, view its usage in the [[https://github.com/FabricMC/fabric-example-mod/blob/master/src/main/java/net/fabricmc/example/mixin/ExampleMixin.java|Fabric Example Mod repo]].