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What IL can do for generics constraints.
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| using System.Numerics; | |
| using System.Runtime.CompilerServices; | |
| using InlineIL; | |
| //Not IDisposable | |
| TestClass.DisposeTest(1); | |
| //TestClass | |
| Console.WriteLine(TestClass.Self(new TestClass())); | |
| //Dispose | |
| TestClass.DisposeUnconstrained(new TestClass()); | |
| //True | |
| Console.WriteLine(TestClass.EqualsUnConstrained(1, 1)); | |
| //3 | |
| Console.WriteLine(TestClass.AddConstrained(1, 2)); | |
| //Unhandled exception. System.Security.VerificationException: Method TestClass.Add: type argument 'T' violates the constraint of type parameter 'T'. | |
| Console.WriteLine(TestClass.AddUnconstrained(1, 2)); | |
| interface IGetSelf<T> | |
| { | |
| static abstract T GetSelf(T a); | |
| } | |
| class TestClass : IDisposable, IGetSelf<TestClass> | |
| { | |
| public void Dispose() | |
| { | |
| Console.WriteLine("Dispose"); | |
| } | |
| public static TestClass GetSelf(TestClass a) => a; | |
| [MethodImpl(MethodImplOptions.AggressiveInlining)] | |
| public static void DisposeTest<T>(T a) | |
| { | |
| if (typeof(T).IsAssignableTo(typeof(IDisposable))) | |
| { | |
| DisposeUnconstrained(a); | |
| } | |
| else | |
| { | |
| Console.WriteLine("Not IDisposable"); | |
| } | |
| } | |
| [MethodImpl(MethodImplOptions.AggressiveInlining)] | |
| public static void DisposeUnconstrained<T>(T a) | |
| { | |
| IL.Emit.Ldarga_S(nameof(a)); | |
| IL.Emit.Constrained<T>(); | |
| IL.Emit.Callvirt(new MethodRef(new TypeRef(typeof(IDisposable)), nameof(Dispose))); | |
| ; | |
| } | |
| public static bool EqualsUnConstrained<T>(T a, T b)// where T : IEquatable<T> | |
| { | |
| IL.Emit.Ldarga_S(nameof(a)); | |
| IL.Emit.Ldarg(nameof(b)); | |
| IL.Emit.Constrained<T>(); | |
| IL.Emit.Callvirt(new MethodRef(new TypeRef(typeof(IEquatable<T>)), nameof(Equals))); | |
| return IL.Return<bool>(); | |
| } | |
| [MethodImpl(MethodImplOptions.AggressiveInlining)] | |
| public static T AddConstrained<T>(T a, T b) where T : INumber<T> | |
| { | |
| IL.Emit.Ldarg(nameof(a)); | |
| IL.Emit.Ldarg(nameof(b)); | |
| IL.Emit.Call(new MethodRef(new TypeRef(typeof(TestClass)), nameof(Add)).MakeGenericMethod(typeof(T))); | |
| return IL.Return<T>(); | |
| } | |
| [MethodImpl(MethodImplOptions.AggressiveInlining)] | |
| public static T AddUnconstrained<T>(T a, T b)//where T : INumber<T> | |
| { | |
| IL.Emit.Ldarg(nameof(a)); | |
| IL.Emit.Ldarg(nameof(b)); | |
| IL.Emit.Constrained<T>(); | |
| IL.Emit.Call(new MethodRef(new TypeRef(typeof(IAdditionOperators<,,>).MakeGenericType(typeof(T),typeof(T),typeof(T))),"op_Addition")); | |
| return IL.Return<T>(); | |
| } | |
| static T Add<T>(T a, T b) where T : INumber<T> | |
| { | |
| return a + b; | |
| } | |
| [MethodImpl(MethodImplOptions.AggressiveInlining)] | |
| public static T Self<T>(T a)//where T : INumber<T> | |
| { | |
| IL.Emit.Ldarg(nameof(a)); | |
| IL.Emit.Constrained<T>(); | |
| IL.Emit.Call(new MethodRef(new TypeRef(typeof(IGetSelf<T>)),"GetSelf")); | |
| return IL.Return<T>(); | |
| } | |
| } |
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