DKNet

Inspect nullable and generic type shapes

Part of DKNet.Fw.Extensions. Use TypeExtensions, PropertyExtensions.IsNullableType and StringExtensions.IsStringOrValueType to classify runtime types.

using System;
using System.Collections.Generic;
using DKNet.Fw.Extensions.Reflection;
using DKNet.Fw.Extensions.Primitives;

Console.WriteLine(typeof(List<int>).IsImplementOf(typeof(IEnumerable<>))); // True
Console.WriteLine(typeof(int?).GetNonNullableType() == typeof(int)); // True
Console.WriteLine(typeof(decimal?).IsNumericType()); // True
Console.WriteLine(typeof(string).IsStringOrValueType()); // True

IsAssignableFrom<T>() and IsAssignableTo<T>() wrap the corresponding Type operations. IsImplementOf(Type?) and IsImplementOf<T>() additionally match open generic interfaces and base definitions.

GetNonNullableType() unwraps Nullable<T> or returns the original type. IsNullableType() only recognizes Nullable<T>, and IsEnumType() also recognizes nullable enums. IsNumericType() accepts integer, floating-point and decimal type codes after unwrapping; the object overload returns false for null. IsStringOrValueType() accepts a nullable Type or PropertyInfo and returns false for null.

⚠️ Gotchas & limits

• IsImplementOf returns false for the same type on both sides, and for either null argument.
• IsNullableType and the Type overload of IsNumericType reject null; null-safe methods do not imply all helpers are null-safe.
• Numeric classification uses Type.GetTypeCode, so enums with an integer underlying type also classify as numeric. This does not validate a value or parse text.
• A reference type remains a reference type even when annotated with nullable reference syntax.

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