WrapOperation

Info

For a more in-depth explanation, see the MixinExtra's Wiki.

Similar to Redirects, WrapOperation lets you replace a method call with your own. However, unlike Redirects, they will stack when several mods attempt to inject into the same one.

Use WrapOperation instead of Redirect when applicable.

Say we have the following code:

public void foo(int param) {
    int a = getInt(param);
    String b = getString(param);
    boolean c = getBool(param);
    doSomething(a, b, c);
}

Instead of using a Redirect, we can wrap the operation as such:

@WrapOperation(method = "foo", at = @At(value = "INVOKE", target = "doSomething(ILjava/lang/String;Z)V"))
private void wrapSomething(Foo instance, int a, String b, boolean c, Operation<Void> original) {
    if (ModConfig.configOption) {
        return doSomethingElse(a, b, c);
    } else {
        return original.call(instance, a, b, c); // we can call the original method using original.call instead of actually calling the method itself
    }
}

This will produce:

public void foo(int param) {
    int a = this.getInt(param);
    String b = this.getString(param);
    boolean c = this.getBool(param);
    if (ModConfig.configOption) {
        doSomethingElse(a, b, c);
    } else {
        doSomething(a, b, c);
    }
}

Warning

You should always return an original.call to maintain compatibility.