ModifyReceiver

Info

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

Say we had a class:

private void foo() {
    ...
    bar.setBar(newBar);
    ...
}

And we want to replace the receiver outright. We can do:

@ModifyReceiver(method = "foo", at = @At(value = "INVOKE", target = "setBar(I)V"))
private void changeReceiver(Bar bar, int newBar) {
    if (newBar > 0) {
        return quux;
    } else {
        return bar;
    }
}

With this, we have conditionally replaced the receiver for the setbar call:

private void foo() {
    ...
    if (newBar > 0) {
        quux.setBar(newBar);
    } else {
        bar.setBar(newBar);
    }
    ...
}

This page is directly based off of LlamaLad7's MixinExtra Wuju page for ModifyReceivers.