有人能告诉我是否有一种方法可以用泛型将泛型类型参数T限制为:
Int16 Int32 Int64 UInt16 UInt32 UInt64
我知道哪里关键字,但不能找到只有这些类型的接口,
喜欢的东西:
static bool IntegerFunction<T>(T value) where T : INumeric
有人能告诉我是否有一种方法可以用泛型将泛型类型参数T限制为:
Int16 Int32 Int64 UInt16 UInt32 UInt64
我知道哪里关键字,但不能找到只有这些类型的接口,
喜欢的东西:
static bool IntegerFunction<T>(T value) where T : INumeric
当前回答
. net数字基元类型不共享任何允许它们用于计算的公共接口。可以定义自己的接口(例如ISignedWholeNumber)来执行这样的操作,定义包含单个Int16、Int32等的结构并实现这些接口,然后有方法接受受ISignedWholeNumber约束的泛型类型,但是必须将数值转换为你的结构类型可能是一个麻烦。
An alternative approach would be to define static class Int64Converter<T> with a static property bool Available {get;}; and static delegates for Int64 GetInt64(T value), T FromInt64(Int64 value), bool TryStoreInt64(Int64 value, ref T dest). The class constructor could use be hard-coded to load delegates for known types, and possibly use Reflection to test whether type T implements methods with the proper names and signatures (in case it's something like a struct which contains an Int64 and represents a number, but has a custom ToString() method). This approach would lose the advantages associated with compile-time type-checking, but would still manage to avoid boxing operations and each type would only have to be "checked" once. After that, operations associated with that type would be replaced with a delegate dispatch.
其他回答
. net数字基元类型不共享任何允许它们用于计算的公共接口。可以定义自己的接口(例如ISignedWholeNumber)来执行这样的操作,定义包含单个Int16、Int32等的结构并实现这些接口,然后有方法接受受ISignedWholeNumber约束的泛型类型,但是必须将数值转换为你的结构类型可能是一个麻烦。
An alternative approach would be to define static class Int64Converter<T> with a static property bool Available {get;}; and static delegates for Int64 GetInt64(T value), T FromInt64(Int64 value), bool TryStoreInt64(Int64 value, ref T dest). The class constructor could use be hard-coded to load delegates for known types, and possibly use Reflection to test whether type T implements methods with the proper names and signatures (in case it's something like a struct which contains an Int64 and represents a number, but has a custom ToString() method). This approach would lose the advantages associated with compile-time type-checking, but would still manage to avoid boxing operations and each type would only have to be "checked" once. After that, operations associated with that type would be replaced with a delegate dispatch.
我会使用一个通用的,你可以处理外部…
/// <summary>
/// Generic object copy of the same type
/// </summary>
/// <typeparam name="T">The type of object to copy</typeparam>
/// <param name="ObjectSource">The source object to copy</param>
public T CopyObject<T>(T ObjectSource)
{
T NewObject = System.Activator.CreateInstance<T>();
foreach (PropertyInfo p in ObjectSource.GetType().GetProperties())
NewObject.GetType().GetProperty(p.Name).SetValue(NewObject, p.GetValue(ObjectSource, null), null);
return NewObject;
}
所有数值类型都是实现IComparable, IComparable<T>, IConvertible, IEquatable<T>, IFormattable的结构体。然而,DateTime也是如此。
所以这个泛型扩展方法是可能的:
public static bool IsNumeric<T>(this T value) where T : struct, IComparable, IComparable<T>, IConvertible, IEquatable<T>, IFormattable =>
typeof(T) != typeof(DateTime);
但是对于实现这些接口的结构体,它将失败,例如:
public struct Foo : IComparable, IComparable<Foo>, IConvertible, IEquatable<Foo>, IFormattable { /* ... */ }
这个非泛型的替代方法性能较差,但保证可以工作:
public static bool IsNumeric(this Type type) =>
type == typeof(sbyte) || type == typeof(byte) ||
type == typeof(short) || type == typeof(ushort) ||
type == typeof(int) || type == typeof(uint) ||
type == typeof(long) || type == typeof(ulong) ||
type == typeof(float) ||
type == typeof(double) ||
type == typeof(decimal);
这个约束存在于。net 7中。
查看这篇。net博客文章和实际文档。
从。net 7开始,你可以使用接口如INumber和IFloatingPoint来创建程序,例如:
using System.Numerics;
Console.WriteLine(Sum(1, 2, 3, 4, 5));
Console.WriteLine(Sum(10.541, 2.645));
Console.WriteLine(Sum(1.55f, 5, 9.41f, 7));
static T Sum<T>(params T[] numbers) where T : INumber<T>
{
T result = T.Zero;
foreach (T item in numbers)
{
result += item;
}
return result;
}
innumber在系统中。数字名称空间。
还有诸如IAdditionOperators和IComparisonOperators这样的接口,因此您可以通用地使用特定的操作符。
目前还没有“好的”解决方案。但是,您可以显著地缩小类型参数,以排除许多与您假设的“INumeric”约束不匹配的情况,如上面haacks所示。
static bool IntegerFunction<T>(T值)where T: IComparable, iformatable, IConvertible, IComparable<T>, IEquatable<T>, struct {…