动态替换一个C＃方法的内容？ [英] Dynamically replace the contents of a C# method?

问题描述

我想要做的是怎么改，当它被称为C＃方法执行，这样我可以这样写：

What I want to do is change how a C# method executes when it is called, so that I can write something like this:

[Distributed]
public DTask<bool> Solve(int n, DEvent<bool> callback)
{
    for (int m = 2; m < n - 1; m += 1)
        if (m % n == 0)
            return false;
    return true;
}

在运行时，我需要能够分析具有分布式属性（我已经可以做），然后插入code之前，函数体执行，并在函数返回之后方法。更重要的是，我需要能够做到这一点，而无需修改code，其中解决被调用或在函数的开始（在编译时;在运行时，这样做是客观的）

At run-time, I need to be able to analyse methods that have the Distributed attribute (which I already can do) and then insert code before the body of the function executes and after the function returns. More importantly, I need to be able to do it without modifying code where Solve is called or at the start of the function (at compile time; doing so at run-time is the objective).

目前，我已经尝试code的该位的（假设t是能够解决存储在类型，m是解决的一个MethodInfo）的：

At the moment I have attempted this bit of code (assume t is the type that Solve is stored in, and m is a MethodInfo of Solve):

private void WrapMethod(Type t, MethodInfo m)
{
    // Generate ILasm for delegate.
    byte[] il = typeof(Dpm).GetMethod("ReplacedSolve").GetMethodBody().GetILAsByteArray();

    // Pin the bytes in the garbage collection.
    GCHandle h = GCHandle.Alloc((object)il, GCHandleType.Pinned);
    IntPtr addr = h.AddrOfPinnedObject();
    int size = il.Length;

    // Swap the method.
    MethodRental.SwapMethodBody(t, m.MetadataToken, addr, size, MethodRental.JitImmediate);
}

public DTask<bool> ReplacedSolve(int n, DEvent<bool> callback)
{
    Console.WriteLine("This was executed instead!");
    return true;
}

不过，MethodRental.SwapMethodBody仅适用于动态模块;而不是那些已经被编译并存储在装配。

However, MethodRental.SwapMethodBody only works on dynamic modules; not those that have already been compiled and stored in the assembly.

所以我在寻找一种方式，切实做好SwapMethodBody对已存储在加载和执行程序集方式

So I'm looking for a way to effectively do SwapMethodBody on a method that is already stored in a loaded and executing assembly.

请注意，这不是一个问题，如果我的方法完全复制到一个动态模块，但在这种情况下，我需要找到一种方法跨越IL复制以及更新所有的呼叫解决（）这样，他们将指向新副本。

Note, it is not an issue if I have to completely copy the method into a dynamic module, but in this case I need to find a way to copy across the IL as well as update all of the calls to Solve() such that they would point to the new copy.

推荐答案

试想影响的，如果这是可能的。例如，您可以替换字符串类的内容和发泄havock。一旦一个方法是由CLR装载它不能被修改。你可以看看AOP和库如城堡DynamicProxy 由嘲笑框架中使用如犀牛制品。

Just think of the implications if this was possible. You could for example replace the contents of the String class and wreak havock. Once a method is loaded by the CLR it cannot be modified. You may take a look at AOP and libraries such as Castle DynamicProxy that are used by mocking frameworks such as Rhino Mocks.

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