MewWeaver - IL Weaving Framework for Unity

Introduction

MewWeaver adds ability of IL Weaving into your project. It depends on Mono.Cecil library.

By IL Weaving, for example, you can add the [MethodProfiling] attribute to measure the execution time of a function. It is possible to easily add functions without breaking the structure of the entire program.

class SomeClass
{
    [MethodProfiling]
    public void DoSomething()
    {
        // Do domething...
    }
}

In result on Log Console

[System.Void SomeClass::DoSomething()] 00:00:00.0000349
[System.Void SomeClass::DoSomething()] 00:00:00.0000002
[System.Void SomeClass::DoSomething()] 00:00:00.0000001
[System.Void SomeClass::DoSomething()] 00:00:00.0000001
[System.Void SomeClass::DoSomething()] 00:00:00.0000004
...

MewWeaver works on Unity2021.3 or later.

Install

Open Unity Package Manager. Select "add package from git URL" and enter the following URL

https://github.com/mewlist/MewWeaver.git?path=Assets/MewWeaver

Samples

BeforeAfterWeaver

MethodProfilingWeaver

Tutorial

Some preparation is needed to weave.

• Custom Attribute
• Static method to inject
• Weaver class

Custom Attribute

A typical Custom Attribute is like this.

[AttributeUsage(AttributeTargets.Method)] 
public class BeforeAttribute : Attribute
{
    public BeforeAttribute() { } 
}

This attribute will put on target method.

[Before]
void TargetMethod()
{
}

Static method to inject

Static method is injected into method having Custom Attribute. If already have a static function, you can use it.

public static class InjectedMethod
{
    public class Before
    {
        public static void Do()
        {
            Debug.Log($"Before Do");
        }
    }
}

Create Weaver

To create new Weaver, define class inherited from IWeaver and implement Weave() method. This class must be placed under Editor folder. Behavior described using a fluent interface, implement like this.

Editor/MyWeaver.cs

public class MyWeaver : IWeaver
{
    public void Weave(AssemblyInjector assemblyInjector)
    {
        assemblyInjector
            .OnAssembly("Assembly-CSharp")
            .OnAttribute<BeforeAttribute>()
            .BeforeDo(Before.Do)
            .Inject();
    }
}

MewWeaver automatically find weavers and modify assemblies.

Injector methods

OnAssembly(assemblyName)

.OnAssembly("Assembly-CSharp")

OnAssembly tells target assembly to weaver. Typically main assembly "Assembly-CSharp" will be specified.

OnMainAssembly()

Same as .OnAssembly("Assembly-CSharp")

.OnMainAssembly()

OnAttribute()

.OnAttribute<BeforeAttribute>()

Specify custom attribute. This attribute be searched as injection method by Weaver.

BeforeDo(staticMethod)

.BeforeDo(Before.Do)

Set Static Method. This method will be injected into beginning of target function.

AfterDo(staticMethod)

.AfterDo(After.Do)

Set Static Method. This method will be injected into end of target function.

Inject()

.Inject()

When this method is called, AssemblyInjector injects code as declared.

Develop Custom IL Injector

Not yet documented.