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copied!<p>Actually, I can't get it to <em>fail</em> - at least, when generating in memory.</p> <p>Let's start simply, with a <code>public readonly</code> field (so we aren't breaking any accessebility rules); my first attempt is as below, and it works fine:</p> <pre><code>using System; using System.Reflection; using System.Reflection.Emit; class Foo { public readonly int i; public int I { get { return i; } } public Foo(int i) { this.i = i; } } static class Program { static void Main() { var setter = CreateWriteAnyInt32Field(typeof(Foo), "i"); var foo = new Foo(123); setter(foo, 42); Console.WriteLine(foo.I); // 42; } static Action<object, int> CreateWriteAnyInt32Field(Type type, string fieldName) { var field = type.GetField(fieldName, BindingFlags.Instance | BindingFlags.Public | BindingFlags.NonPublic); var method = new DynamicMethod("evil", null, new[] { typeof(object), typeof(int) }); var il = method.GetILGenerator(); il.Emit(OpCodes.Ldarg_0); il.Emit(OpCodes.Castclass, type); il.Emit(OpCodes.Ldarg_1); il.Emit(OpCodes.Stfld, field); il.Emit(OpCodes.Ret); return (Action<object, int>)method.CreateDelegate(typeof(Action<object, int>)); } } </code></pre> <p>The only time it gets interesting is if the field is <code>private</code>:</p> <pre><code>private readonly int i; </code></pre> <p>The code above then gives the oh-so-vague:</p> <blockquote> <p>Operation could destabilize the runtime.</p> </blockquote> <p>But we get around that by pretending that the method is inside the field's declaring type:</p> <pre><code>var method = new DynamicMethod("evil", null, new[] { typeof(object), typeof(int) }, field.DeclaringType); </code></pre> <p>Some other internal checks can be done by enabling <code>skipVisibility</code>:</p> <pre><code>var method = new DynamicMethod("evil", null, new[] { typeof(object), typeof(int) }, field.DeclaringType, true); </code></pre> <p>However, note that not all of this is possible if generating standalone assemblies. You are held to much higher standards when creating actual dlls. For this reason, the <code>precompiler</code> tool (to pre-generate assemblies) cannot handle quite the same range of scenarios that the in-memory meta-programming code can.</p>

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