有没有人有一个快速的片段或指示如何检查给定的类是否支持>,=和<操作符? 给定一个传入的对象,我正在寻找实现以下逻辑的代码:
If GetType(someObj).SupportsScalarComparisons() Then ...
我不知道这是反映的情况,还是?提前致谢.
我认为这是一个有趣的问题,所以我决定使用反射来提出解决方案. (我不知道除了反思之外还有另一种方式.)
Imports System.Reflection Module MainModule Sub Main() 'primitive,value type If GetType(Integer).SupportsScalarComparisons Then Debug.WriteLine("Integer supports comparisions") Else Debug.WriteLine("Integer does not support comparisions") End If 'non-primitive,value type If GetType(Decimal).SupportsScalarComparisons Then Debug.WriteLine("Decimal supports comparisions") Else Debug.WriteLine("Decimal does not support comparisions") End If 'non-primitive,object type If GetType(Version).SupportsScalarComparisons Then Debug.WriteLine("Version supports comparisions") Else Debug.WriteLine("Version does not support comparisions") End If 'non-primitive,object type If GetType(String).SupportsScalarComparisons Then Debug.WriteLine("String supports comparisions") Else Debug.WriteLine("String does not support comparisions") End If 'Integer supports comparisions 'Decimal supports comparisions 'Version supports comparisions 'String does not support comparisions End Sub Public Sub Dump(ByVal type As Type) Dim oMethod() As MethodInfo = type.getmethods(BindingFlags.Static Or BindingFlags.Public) For Each o As MethodInfo In oMethod Debug.WriteLine(o.Name) Next End Sub End Module Public Module TypeExtensions <System.Runtime.CompilerServices.Extension()> _ Public Function SupportsScalarComparisons(ByVal obj As Type) As Boolean Static Methods() As String = {"op_GreaterThan","op_Equality","op_Lessthan"} If obj.IsPrimitive Then Return True End If For Each sMethodName As String In Methods Dim oMethod As MethodInfo = obj.getmethod(sMethodName,BindingFlags.Public Or BindingFlags.Static) If oMethod Is nothing Then 'does not support Return False End If Next Return True 'List is from MSDN Library index 'op_Addition 'op_BitwiseAnd 'op_BitwiSEOr 'op_Decrement 'op_Division 'op_Equality 'op_ExculsiveOr 'op_Explicit 'op_False 'op_GreaterThan 'op_GreaterThanorEqual 'op_Implicit 'op_Increment 'op_Inequality 'op_LogicalNot 'op_Lessthan 'op_LessthanorEqual 'op_Modulus 'op_Multiply 'op_OnesComplement 'op_Subtraction 'op_True 'op_UnaryNegation 'op_UnaryPlus End Function End Module
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