CorePatcher short helpers

A prefix runs your method before the game method, a postfix runs it after, and a finalizer runs it when the game method throws an error. These helpers set one of those up in one line. The owner is your mod id (see Owner).

CorePatcher one-line prefix, postfix and finalizer helpers

Call one of these with the game method, your handler’s type and name, and your mod id as owner.

public static class CorePatcher
{
    public static bool Prefix(Type target, string method, Type handlerType, string handlerName, string owner);
    public static bool Prefix(Type target, string method, Type[] args, Type handlerType, string handlerName, string owner);
    public static bool Postfix(Type target, string method, Type handlerType, string handlerName, string owner);
    public static bool Postfix(Type target, string method, Type[] args, Type handlerType, string handlerName, string owner);
    public static bool Finalizer(Type target, string method, Type handlerType, string handlerName, string owner);
    public static bool Finalizer(Type target, string method, Type[] args, Type handlerType, string handlerName, string owner);
}

Method	Returns	What it does
`Prefix(target, method, handlerType, handlerName, owner)`	`bool`	Runs your method before a game method.
`Prefix(target, method, args, handlerType, handlerName, owner)`	`bool`	The same, for a game method with several versions.
`Postfix(target, method, handlerType, handlerName, owner)`	`bool`	Runs your method after a game method.
`Postfix(target, method, args, handlerType, handlerName, owner)`	`bool`	The same, for a game method with several versions.
`Finalizer(target, method, handlerType, handlerName, owner)`	`bool`	Runs your method when a game method throws an error.
`Finalizer(target, method, args, handlerType, handlerName, owner)`	`bool`	The same, for a game method with several versions.

Things to know

The result is true when the change was made and false when it was not. It is false when it failed, and the reason goes to <owner>.log, or when the owner has been turned off. (Each helper calls CorePatcher.Patch with only the one handler it names filled in and its core argument set to false, and the result is the bool that Patch returns.)
The handler can keep its Harmony settings. [HarmonyPriority], [HarmonyBefore] and [HarmonyAfter] on your method still apply, the same as with Patch. See Harmony.

Limits

handlerName is the name of a static method on handlerType, and it may be private. If there is no such method, you get a MissingMethodException.
Use an owner that is not reserved. A reserved owner throws an ArgumentException. The rules for the owner are the rules of CorePatcher.Patch, described on the framework core page.
Without args, the name must match exactly one method on the target. The method may be public or private, and an instance method or a static one. A name that is missing, or that has several versions, returns false and writes one line to the owner’s log. For a method with several versions, use the version with Type[] args.

Example

The long way and the short way to add a postfix, side by side:

MethodInfo postfix = typeof(Helpers).GetMethod("AfterDay", BindingFlags.Static | BindingFlags.NonPublic);
bool longWay = CorePatcher.Patch(typeof(TimeOfDayAzure), "IncreaseDayCounter", null, null, postfix, null, false, "example.helpers");
bool shortWay = CorePatcher.Postfix(typeof(TimeOfDayAzure), "IncreaseDayCounter", typeof(Helpers), "AfterDay", "example.helpers");