Modlet

{
    "tasks": [
        {
            "label": "compile",
            "type": "shell",
            "command": "mcs",
            "args": [
                "-target:library",
                "-warn:0",
                "-o+",
                "-unsafe",
                "-r:${userHome}/.steam/steam/steamapps/common/7 Days To Die/7DaysToDie_Data/Managed/0Harmony.dll",
                "-r:${userHome}/.steam/steam/steamapps/common/7 Days To Die/7DaysToDie_Data/Managed/Assembly-CSharp.dll",
                "-r:${userHome}/.steam/steam/steamapps/common/7 Days To Die/7DaysToDie_Data/Managed/UnityEngine.CoreModule.dll",
                "-langversion:latest",
                "-out:${workspaceFolderBasename}.dll",
                "**/*.cs",
            ],
            "options": {
                "cwd": "${workspaceFolder}"
            },
            "problemMatcher": [],
            "group": {
                "kind": "build",
                "isDefault": true
            }
        }
    ]
}

using HarmonyLib;
using System.Reflection;
using UnityEngine;

public class TestProject_HarmonyInit : IModApi
{
    public void InitMod(Mod _instance)
    {
        Debug.Log($" Loading Patch: {GetType()} Mod: {_instance.ModInfo.Name}");
        var harmony = new Harmony(GetType().ToString());
        harmony.PatchAll(Assembly.GetExecutingAssembly());
    }
}

using HarmonyLib;

public class FifteenSlotToolbelt_Inventory
{
    /**
     * <summary>New slot number for Toolbelt</summary>
     */
    public const int INVENTORY_SLOT_NEW = 15;

    [HarmonyPatch(typeof(Inventory))]
    [HarmonyPatch("get_PUBLIC_SLOTS")]
    public class FifteenSlotToolbelt_harmony_Inventory_get_PUBLIC_SLOTS
    {
        public static void Postfix(ref int __result)
        {
            __result = INVENTORY_SLOT_NEW;
        }
    }
}

<modconfig>
    <set xpath="/windows/window[@name='windowToolbelt']/@width">1128</set><!-- ツールベルト ウィンドウサイズ -->
    <set xpath="/windows/window[@name='windowToolbelt']/@pos">-575,92</set><!-- ツールベルト ウィンドウをどこに表示させるか、親コンポーネントからの相対位置 -->
    <set xpath="/windows/window[@name='windowToolbelt']/rect/rect[@controller='Toolbelt']/grid[@name='inventory']/@cols">15</set><!-- スロットは15個 -->

    <set xpath="/windows/window[@name='windowToolbelt']/rect/rect[@controller='Toolbelt']/grid[@name='inventory2']/@visible">false</set><!-- 2行目は非表示 -->

    <set xpath="/windows/window[@name='windowToolbelt']/rect/sprite[@fill='{xp}']/@width">1125</set><!-- 大きくなったウィンドウサイズに経験値インジケータを合わせる -->

    <set xpath="/windows/window[@name='windowToolbelt']/rect/rect[@stat_type='Food']/@width">565</set><!-- 食料インジケータも合わせる -->
    <set xpath="/windows/window[@name='windowToolbelt']/rect/rect[@stat_type='Food']/filledsprite[@name='BarContent']/@width">563</set>

    <set xpath="/windows/window[@name='windowToolbelt']/rect/rect[@stat_type='Water']/@width">565</set><!-- 水分インジケータも合わせる -->
    <set xpath="/windows/window[@name='windowToolbelt']/rect/rect[@stat_type='Water']/@pos">563,-77</set>
    <set xpath="/windows/window[@name='windowToolbelt']/rect/rect[@stat_type='Water']/filledsprite[@name='BarContent']/@width">562</set>
</modconfig>

using UnityEngine;

public class OriginalCode
{
    public void Test(int counter, string name)
    {
        // ...
    }
}

[HarmonyPatch(typeof(OriginalCode))]
[HarmonyPatch("Test")]
class Patch
{
    static void Prefix(int counter, ref string name)
    {
        Debug.Log("counter = " + counter); // 値を読む
        name = "test"; // ref キーワードを設定しているため、name が変更された状態でオリジナルメソッドの処理が走る
    }
}

public class OriginalCode
{
    public string Test(int counter, string name)
    {
        // ...
    }
}

[HarmonyPatch(typeof(OriginalCode))]
[HarmonyPatch("Test")]
class Patch
{
    static bool Prefix(ref string __result, int counter, string name)
    {
        __result = "test"; // 戻り値を書き換える
        return false; // false を返すと、オリジナルメソッドの中身は実行されない
    }
}

public class OriginalCode
{
    public string Test()
    {
        return this.name;
    }
}

[HarmonyPatch(typeof(OriginalCode))]
[HarmonyPatch("Test")]
class Patch
{
    static void Postfix(ref string __result)
    {
        if (__result == "test") {
            __result = "modified";
        }
    }
}

public class OriginalCode
{
    public IEnumerable<int> GetNumbers()
    {
        yield return 1;
        yield return 2;
        yield return 3;
    }
}

[HarmonyPatch(typeof(OriginalCode))]
[HarmonyPatch("GetNumbers")]
class Patch
{
    static IEnumerable<int> Postfix(IEnumerable<int> __result)
    {
        yield return 0;
        foreach (var value in __result)
            if (value > 1)
                yield return value * 5;
        yield return 60;
    }
    // 戻り値は [ 1, 2, 3 ] から [ 0, 10, 15, 60 ] に変更される
}

using System.Diagnostics;
using UnityEngine;

public class OriginalCode
{
    public string Test(int counter, string name)
    {
        // ...
    }
}

[HarmonyPatch(typeof(OriginalCode))]
[HarmonyPatch("Test")]
class Patch
{
    static void Prefix(out Stopwatch __state)
    {
        __state = new Stopwatch(); // 独自の値を設定
        __state.Start();
    }

    static void Postfix(Stopwatch __state)
    {
        __state.Stop();
        Debug.Log(__state.Elapsed.ToString()); // 実行時間をログに表示
    }
}