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Switch DynamicMethod samples from regions to methods
Restructure DynamicMethod.Examples.cs to use self-contained static methods instead of #region/#endregion directives. Each method creates its own DynamicMethod and is independently runnable — addressing feedback that samples should be copy-paste compilable. Three methods replace the many small regions: - MetadataAndProperties: Name, DeclaringType, Module, Attributes, etc. - DefineParameterAndGetParameters: parameter metadata - GetILGeneratorAndInvoke: IL emission, delegates, and Invoke Update <code> tags in DynamicMethod.cs and samples.json to use method= instead of region= for Examples.cs entries. Overview.cs and CtorOwnerType.cs retain their existing region-based approach (single self-contained regions). Addresses feedback from jkotas on PR #124407. Co-authored-by: Copilot <223556219+Copilot@users.noreply.github.com>
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‎src/libraries/System.Private.CoreLib/samples/System/Reflection/Emit/DynamicMethod.Examples.cs‎

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// Licensed to the .NET Foundation under one or more agreements.
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// The .NET Foundation licenses this file to you under the MIT license.
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// Runnable examples for DynamicMethod XML doc comments.
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// Each #region is referenced by <code> tags in DynamicMethod.cs.
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// Each static method is a self-contained sample referenced by <code> tags in DynamicMethod.cs.
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// Run: dotnet run DynamicMethod.Examples.cs
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using System.Globalization;
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using System.Reflection;
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using System.Reflection.Emit;
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// Create a DynamicMethod shared by the property/method examples below.
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DynamicMethod hello = new("Hello", typeof(int), [typeof(string), typeof(int)], typeof(string).Module);
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int failures = 0;
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DynamicMethodExamples.MetadataAndProperties();
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DynamicMethodExamples.DefineParameterAndGetParameters();
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DynamicMethodExamples.GetILGeneratorAndInvoke();
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void Fail(string name, string message)
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{
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Console.Error.WriteLine($"FAIL: {name} — {message}");
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failures++;
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}
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Console.WriteLine("All examples passed.");
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return 0;
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#region Name
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// The name specified when the dynamic method was created.
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Console.WriteLine($"Name: {hello.Name}");
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#endregion
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if (hello.Name != "Hello") Fail("Name", $"Expected 'Hello', got '{hello.Name}'");
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#region DeclaringType
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// DeclaringType is always null for dynamic methods.
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Console.WriteLine($"DeclaringType: {hello.DeclaringType?.ToString() ?? "(null)"}");
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#endregion
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if (hello.DeclaringType is not null) Fail("DeclaringType", "Expected null");
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#region ReflectedType
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// ReflectedType is always null for dynamic methods.
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Console.WriteLine($"ReflectedType: {hello.ReflectedType?.ToString() ?? "(null)"}");
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#endregion
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if (hello.ReflectedType is not null) Fail("ReflectedType", "Expected null");
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#region Module
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// The module the dynamic method is associated with.
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Console.WriteLine($"Module: {hello.Module}");
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#endregion
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if (hello.Module != typeof(string).Module) Fail("Module", "Expected System.Private.CoreLib module");
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#region Attributes
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// Dynamic methods always have Public | Static attributes.
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Console.WriteLine($"Attributes: {hello.Attributes}");
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#endregion
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if (hello.Attributes != (MethodAttributes.Public | MethodAttributes.Static))
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Fail("Attributes", $"Expected Public | Static, got {hello.Attributes}");
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#region CallingConvention
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// Dynamic methods always use Standard calling convention.
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Console.WriteLine($"CallingConvention: {hello.CallingConvention}");
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#endregion
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if (hello.CallingConvention != CallingConventions.Standard)
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Fail("CallingConvention", $"Expected Standard, got {hello.CallingConvention}");
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#region InitLocals
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// InitLocals defaults to true — local variables are zero-initialized.
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Console.WriteLine($"InitLocals: {hello.InitLocals}");
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#endregion
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if (!hello.InitLocals) Fail("InitLocals", "Expected true");
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#region ReturnType
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// The return type specified when the dynamic method was created.
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Console.WriteLine($"ReturnType: {hello.ReturnType}");
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#endregion
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if (hello.ReturnType != typeof(int)) Fail("ReturnType", $"Expected Int32, got {hello.ReturnType}");
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#region ReturnTypeCustomAttributes
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// At present there is no way to set custom attributes on the return type,
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// so the list is always empty.
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ICustomAttributeProvider caProvider = hello.ReturnTypeCustomAttributes;
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object[] returnAttributes = caProvider.GetCustomAttributes(true);
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Console.WriteLine($"Return type custom attributes: {returnAttributes.Length}");
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#endregion
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if (returnAttributes.Length != 0) Fail("ReturnTypeCustomAttributes", "Expected 0 attributes");
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#region DefineParameter
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// Optionally add parameter metadata (useful for debugging).
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hello.DefineParameter(1, ParameterAttributes.In, "message");
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hello.DefineParameter(2, ParameterAttributes.In, "valueToReturn");
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#endregion
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#region GetParameters
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// Retrieve parameter info after calling DefineParameter.
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ParameterInfo[] parameters = hello.GetParameters();
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foreach (ParameterInfo p in parameters)
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Console.WriteLine($" Param: {p.Name}, {p.ParameterType}, {p.Attributes}");
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#endregion
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if (parameters.Length != 2) Fail("GetParameters", $"Expected 2 parameters, got {parameters.Length}");
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#region ToString
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// ToString returns the signature: return type, name, and parameter types.
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string sig = hello.ToString();
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Console.WriteLine($"ToString: {sig}");
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#endregion
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if (!sig.Contains("Hello")) Fail("ToString", $"Expected signature to contain 'Hello'");
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// Emit a method body so we can test CreateDelegate and Invoke.
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MethodInfo writeString = typeof(Console).GetMethod("WriteLine", [typeof(string)])!;
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#region GetILGenerator
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// Get an ILGenerator to emit the method body.
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ILGenerator il = hello.GetILGenerator();
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il.Emit(OpCodes.Ldarg_0);
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il.EmitCall(OpCodes.Call, writeString, null);
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il.Emit(OpCodes.Ldarg_1);
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il.Emit(OpCodes.Ret);
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#endregion
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#region CreateDelegate
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// Create a strongly-typed delegate for the dynamic method.
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Func<string, int, int> hi = hello.CreateDelegate<Func<string, int, int>>();
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int retval = hi("Hello from delegate!", 42);
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Console.WriteLine($"Delegate returned: {retval}");
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#endregion
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if (retval != 42) Fail("CreateDelegate", $"Expected 42, got {retval}");
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#region Invoke
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// Invoke the dynamic method via reflection (slower than a delegate).
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object? objRet = hello.Invoke(null, BindingFlags.ExactBinding, null,
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["Hello from Invoke!", 99], CultureInfo.InvariantCulture);
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Console.WriteLine($"Invoke returned: {objRet}");
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#endregion
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if (objRet is not 99) Fail("Invoke", $"Expected 99, got {objRet}");
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if (failures > 0)
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class DynamicMethodExamples
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{
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Console.Error.WriteLine($"\n{failures} example(s) failed.");
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return 1;
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/// <summary>
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/// Shows the metadata properties of a DynamicMethod: Name, DeclaringType, ReflectedType,
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/// Module, Attributes, CallingConvention, ReturnType, ReturnTypeCustomAttributes, InitLocals,
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/// and ToString.
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/// </summary>
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public static void MetadataAndProperties()
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{
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// Create a dynamic method associated with a module.
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DynamicMethod hello = new("Hello", typeof(int), [typeof(string), typeof(int)], typeof(string).Module);
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// Name: the name specified at creation.
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Console.WriteLine($"Name: {hello.Name}");
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// DeclaringType is always null for dynamic methods.
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Console.WriteLine($"DeclaringType: {hello.DeclaringType?.ToString() ?? "(null)"}");
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// ReflectedType is always null for dynamic methods.
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Console.WriteLine($"ReflectedType: {hello.ReflectedType?.ToString() ?? "(null)"}");
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// Module: the module the dynamic method is associated with.
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Console.WriteLine($"Module: {hello.Module}");
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// Attributes are always Public | Static.
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Console.WriteLine($"Attributes: {hello.Attributes}");
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// CallingConvention is always Standard.
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Console.WriteLine($"CallingConvention: {hello.CallingConvention}");
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// ReturnType: the return type specified at creation.
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Console.WriteLine($"ReturnType: {hello.ReturnType}");
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// ReturnTypeCustomAttributes: no way to set custom attributes on the return type.
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ICustomAttributeProvider caProvider = hello.ReturnTypeCustomAttributes;
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object[] returnAttributes = caProvider.GetCustomAttributes(true);
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Console.WriteLine($"Return type custom attributes: {returnAttributes.Length}");
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// InitLocals defaults to true — local variables are zero-initialized.
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Console.WriteLine($"InitLocals: {hello.InitLocals}");
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// ToString returns the method signature (return type, name, parameter types).
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Console.WriteLine($"ToString: {hello.ToString()}");
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}
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/// <summary>
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/// Shows DefineParameter and GetParameters: adding parameter metadata and retrieving it.
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/// </summary>
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public static void DefineParameterAndGetParameters()
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{
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DynamicMethod hello = new("Hello", typeof(int), [typeof(string), typeof(int)], typeof(string).Module);
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// DefineParameter adds metadata such as name and attributes.
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// Parameter positions are 1-based; position 0 refers to the return value.
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hello.DefineParameter(1, ParameterAttributes.In, "message");
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hello.DefineParameter(2, ParameterAttributes.In, "valueToReturn");
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// GetParameters retrieves the parameter info.
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ParameterInfo[] parameters = hello.GetParameters();
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foreach (ParameterInfo p in parameters)
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Console.WriteLine($" Param: {p.Name}, {p.ParameterType}, {p.Attributes}");
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}
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/// <summary>
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/// Shows GetILGenerator, CreateDelegate, and Invoke: emitting a method body and calling it.
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/// </summary>
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public static void GetILGeneratorAndInvoke()
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{
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DynamicMethod hello = new("Hello", typeof(int), [typeof(string), typeof(int)], typeof(string).Module);
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MethodInfo writeString = typeof(Console).GetMethod("WriteLine", [typeof(string)])!;
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// GetILGenerator returns an ILGenerator for emitting the method body.
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ILGenerator il = hello.GetILGenerator();
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il.Emit(OpCodes.Ldarg_0); // push first arg (string)
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il.EmitCall(OpCodes.Call, writeString, null); // Console.WriteLine(string)
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il.Emit(OpCodes.Ldarg_1); // push second arg (int)
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il.Emit(OpCodes.Ret); // return it
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// CreateDelegate produces a strongly-typed delegate for the dynamic method.
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Func<string, int, int> hi = hello.CreateDelegate<Func<string, int, int>>();
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int retval = hi("Hello from delegate!", 42);
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Console.WriteLine($"Delegate returned: {retval}");
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// Invoke calls the dynamic method via reflection (slower than a delegate).
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object? objRet = hello.Invoke(null, BindingFlags.ExactBinding, null,
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["Hello from Invoke!", 99], CultureInfo.InvariantCulture);
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Console.WriteLine($"Invoke returned: {objRet}");
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}
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}
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Console.WriteLine("\nAll examples passed.");
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return 0;

‎src/libraries/System.Private.CoreLib/samples/samples.json‎

Lines changed: 16 additions & 16 deletions
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"T:System.Reflection.Emit.DynamicMethod": { "file": "System/Reflection/Emit/DynamicMethod.Overview.cs", "region": "CreateAndInvoke", "title": "Creating and invoking a DynamicMethod" },
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"M:System.Reflection.Emit.DynamicMethod.#ctor(System.String,System.Type,System.Type[],System.Reflection.Module)": { "file": "System/Reflection/Emit/DynamicMethod.Overview.cs", "region": "CreateAndInvoke", "title": "Creating a DynamicMethod associated with a module" },
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"M:System.Reflection.Emit.DynamicMethod.#ctor(System.String,System.Type,System.Type[],System.Type)": { "file": "System/Reflection/Emit/DynamicMethod.CtorOwnerType.cs", "region": "OwnerTypeAccess", "title": "Creating a DynamicMethod with an owner type" },
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"P:System.Reflection.Emit.DynamicMethod.Name": { "file": "System/Reflection/Emit/DynamicMethod.Examples.cs", "region": "Name", "title": "Getting the name of a DynamicMethod" },
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"P:System.Reflection.Emit.DynamicMethod.DeclaringType": { "file": "System/Reflection/Emit/DynamicMethod.Examples.cs", "region": "DeclaringType", "title": "Getting the declaring type of a DynamicMethod" },
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"P:System.Reflection.Emit.DynamicMethod.ReflectedType": { "file": "System/Reflection/Emit/DynamicMethod.Examples.cs", "region": "ReflectedType", "title": "Getting the reflected type of a DynamicMethod" },
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"P:System.Reflection.Emit.DynamicMethod.Module": { "file": "System/Reflection/Emit/DynamicMethod.Examples.cs", "region": "Module", "title": "Getting the module of a DynamicMethod" },
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"P:System.Reflection.Emit.DynamicMethod.Attributes": { "file": "System/Reflection/Emit/DynamicMethod.Examples.cs", "region": "Attributes", "title": "Getting the attributes of a DynamicMethod" },
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"P:System.Reflection.Emit.DynamicMethod.CallingConvention": { "file": "System/Reflection/Emit/DynamicMethod.Examples.cs", "region": "CallingConvention", "title": "Getting the calling convention of a DynamicMethod" },
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"P:System.Reflection.Emit.DynamicMethod.ReturnType": { "file": "System/Reflection/Emit/DynamicMethod.Examples.cs", "region": "ReturnType", "title": "Getting the return type of a DynamicMethod" },
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"P:System.Reflection.Emit.DynamicMethod.ReturnTypeCustomAttributes": { "file": "System/Reflection/Emit/DynamicMethod.Examples.cs", "region": "ReturnTypeCustomAttributes", "title": "Getting return type custom attributes" },
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"P:System.Reflection.Emit.DynamicMethod.InitLocals": { "file": "System/Reflection/Emit/DynamicMethod.Examples.cs", "region": "InitLocals", "title": "Checking InitLocals on a DynamicMethod" },
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"M:System.Reflection.Emit.DynamicMethod.ToString": { "file": "System/Reflection/Emit/DynamicMethod.Examples.cs", "region": "ToString", "title": "Getting the string representation of a DynamicMethod" },
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"M:System.Reflection.Emit.DynamicMethod.GetParameters": { "file": "System/Reflection/Emit/DynamicMethod.Examples.cs", "region": "GetParameters", "title": "Getting parameter info from a DynamicMethod" },
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"M:System.Reflection.Emit.DynamicMethod.DefineParameter(System.Int32,System.Reflection.ParameterAttributes,System.String)": { "file": "System/Reflection/Emit/DynamicMethod.Examples.cs", "region": "DefineParameter", "title": "Defining parameters on a DynamicMethod" },
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"M:System.Reflection.Emit.DynamicMethod.GetILGenerator": { "file": "System/Reflection/Emit/DynamicMethod.Examples.cs", "region": "GetILGenerator", "title": "Getting the IL generator for a DynamicMethod" },
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"M:System.Reflection.Emit.DynamicMethod.GetILGenerator(System.Int32)": { "file": "System/Reflection/Emit/DynamicMethod.Examples.cs", "region": "GetILGenerator", "title": "Getting the IL generator for a DynamicMethod" },
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"M:System.Reflection.Emit.DynamicMethod.CreateDelegate(System.Type)": { "file": "System/Reflection/Emit/DynamicMethod.Examples.cs", "region": "CreateDelegate", "title": "Creating a delegate from a DynamicMethod" },
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"P:System.Reflection.Emit.DynamicMethod.Name": { "file": "System/Reflection/Emit/DynamicMethod.Examples.cs", "method": "MetadataAndProperties", "title": "DynamicMethod metadata properties" },
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"P:System.Reflection.Emit.DynamicMethod.DeclaringType": { "file": "System/Reflection/Emit/DynamicMethod.Examples.cs", "method": "MetadataAndProperties", "title": "DynamicMethod metadata properties" },
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"P:System.Reflection.Emit.DynamicMethod.ReflectedType": { "file": "System/Reflection/Emit/DynamicMethod.Examples.cs", "method": "MetadataAndProperties", "title": "DynamicMethod metadata properties" },
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"P:System.Reflection.Emit.DynamicMethod.Module": { "file": "System/Reflection/Emit/DynamicMethod.Examples.cs", "method": "MetadataAndProperties", "title": "DynamicMethod metadata properties" },
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"P:System.Reflection.Emit.DynamicMethod.Attributes": { "file": "System/Reflection/Emit/DynamicMethod.Examples.cs", "method": "MetadataAndProperties", "title": "DynamicMethod metadata properties" },
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"P:System.Reflection.Emit.DynamicMethod.CallingConvention": { "file": "System/Reflection/Emit/DynamicMethod.Examples.cs", "method": "MetadataAndProperties", "title": "DynamicMethod metadata properties" },
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"P:System.Reflection.Emit.DynamicMethod.ReturnType": { "file": "System/Reflection/Emit/DynamicMethod.Examples.cs", "method": "MetadataAndProperties", "title": "DynamicMethod metadata properties" },
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"P:System.Reflection.Emit.DynamicMethod.ReturnTypeCustomAttributes": { "file": "System/Reflection/Emit/DynamicMethod.Examples.cs", "method": "MetadataAndProperties", "title": "DynamicMethod metadata properties" },
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"P:System.Reflection.Emit.DynamicMethod.InitLocals": { "file": "System/Reflection/Emit/DynamicMethod.Examples.cs", "method": "MetadataAndProperties", "title": "DynamicMethod metadata properties" },
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"M:System.Reflection.Emit.DynamicMethod.ToString": { "file": "System/Reflection/Emit/DynamicMethod.Examples.cs", "method": "MetadataAndProperties", "title": "DynamicMethod metadata properties" },
15+
"M:System.Reflection.Emit.DynamicMethod.GetParameters": { "file": "System/Reflection/Emit/DynamicMethod.Examples.cs", "method": "DefineParameterAndGetParameters", "title": "Defining and retrieving DynamicMethod parameters" },
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"M:System.Reflection.Emit.DynamicMethod.DefineParameter(System.Int32,System.Reflection.ParameterAttributes,System.String)": { "file": "System/Reflection/Emit/DynamicMethod.Examples.cs", "method": "DefineParameterAndGetParameters", "title": "Defining and retrieving DynamicMethod parameters" },
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"M:System.Reflection.Emit.DynamicMethod.GetILGenerator": { "file": "System/Reflection/Emit/DynamicMethod.Examples.cs", "method": "GetILGeneratorAndInvoke", "title": "Emitting IL and invoking a DynamicMethod" },
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"M:System.Reflection.Emit.DynamicMethod.GetILGenerator(System.Int32)": { "file": "System/Reflection/Emit/DynamicMethod.Examples.cs", "method": "GetILGeneratorAndInvoke", "title": "Emitting IL and invoking a DynamicMethod" },
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"M:System.Reflection.Emit.DynamicMethod.CreateDelegate(System.Type)": { "file": "System/Reflection/Emit/DynamicMethod.Examples.cs", "method": "GetILGeneratorAndInvoke", "title": "Emitting IL and invoking a DynamicMethod" },
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"M:System.Reflection.Emit.DynamicMethod.CreateDelegate(System.Type,System.Object)": { "file": "System/Reflection/Emit/DynamicMethod.CtorOwnerType.cs", "region": "OwnerTypeAccess", "title": "Creating a bound delegate from a DynamicMethod" },
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"M:System.Reflection.Emit.DynamicMethod.Invoke(System.Object,System.Reflection.BindingFlags,System.Reflection.Binder,System.Object[],System.Globalization.CultureInfo)": { "file": "System/Reflection/Emit/DynamicMethod.Examples.cs", "region": "Invoke", "title": "Invoking a DynamicMethod via reflection" }
21+
"M:System.Reflection.Emit.DynamicMethod.Invoke(System.Object,System.Reflection.BindingFlags,System.Reflection.Binder,System.Object[],System.Globalization.CultureInfo)": { "file": "System/Reflection/Emit/DynamicMethod.Examples.cs", "method": "GetILGeneratorAndInvoke", "title": "Emitting IL and invoking a DynamicMethod" }
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}

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