DynamicObject.TryBinaryOperation 方法

定義

命名空間:

System.Dynamic

組件:

System.Linq.Expressions.dll

來源:

DynamicObject.cs

提供二進位運算的實作。 衍生自 DynamicObject 類別的類別可以覆寫這個方法，以指定加法和乘法這類運算的動態行為。

public:
 virtual bool TryBinaryOperation(System::Dynamic::BinaryOperationBinder ^ binder, System::Object ^ arg, [Runtime::InteropServices::Out] System::Object ^ % result);

public virtual bool TryBinaryOperation (System.Dynamic.BinaryOperationBinder binder, object arg, out object? result);

abstract member TryBinaryOperation : System.Dynamic.BinaryOperationBinder * obj * obj -> bool
override this.TryBinaryOperation : System.Dynamic.BinaryOperationBinder * obj * obj -> bool

Public Overridable Function TryBinaryOperation (binder As BinaryOperationBinder, arg As Object, ByRef result As Object) As Boolean

參數

binder

BinaryOperationBinder

提供二進位運算的相關資訊。 屬性會 binder.Operation 傳 ExpressionType 回 物件。 例如，針對 sum = first + second 語句，其中 first 和 second 衍生自 DynamicObject 類別， binder.Operation 會傳 ExpressionType.Add 回 。

arg

Object

二進位運算的右運算元。 例如，針對 sum = first + second 語句，其中 first 和 second 衍生自 DynamicObject 類別， arg 等於 second 。

result

Object

二進位運算的結果。

傳回

Boolean

如果作業成功，則為 true，否則為 false。 如果這個方法傳回 false，語言的執行階段繫結器會決定行為。 (在大多數情況下，將會擲回特定語言的執行階段例外狀況)。

範例

假設您需要資料結構來儲存數位的文字和數值表示，而且您想要定義基本的數學運算，例如這類資料的加法和減法。

下列程式碼範例示範 DynamicNumber 衍生自 類別的 DynamicObject 類別。 DynamicNumber 會 TryBinaryOperation 覆寫 方法來啟用數學運算。 它也會覆寫 TrySetMember 和 TryGetMember 方法，以啟用元素的存取權。

在此範例中，僅支援加法和減法運算。 如果您嘗試撰寫類似 resultNumber = firstNumber*secondNumber 的語句，則會擲回運行時例外狀況。

// Add using System.Linq.Expressions;
// to the beginning of the file.

// The class derived from DynamicObject.
public class DynamicNumber : DynamicObject
{
    // The inner dictionary to store field names and values.
    Dictionary<string, object> dictionary
        = new Dictionary<string, object>();

    // Get the property value.
    public override bool TryGetMember(
        GetMemberBinder binder, out object result)
    {
        return dictionary.TryGetValue(binder.Name, out result);
    }

    // Set the property value.
    public override bool TrySetMember(
        SetMemberBinder binder, object value)
    {
        dictionary[binder.Name] = value;
        return true;
    }

    // Perform the binary operation.
    public override bool TryBinaryOperation(
        BinaryOperationBinder binder, object arg, out object result)
    {
        // The Textual property contains the textual representaion
        // of two numbers, in addition to the name
        // of the binary operation.
        string resultTextual =
            dictionary["Textual"].ToString() + " "
            + binder.Operation + " " +
            ((DynamicNumber)arg).dictionary["Textual"].ToString();

        int resultNumeric;

        // Checking what type of operation is being performed.
        switch (binder.Operation)
        {
            // Proccessing mathematical addition (a + b).
            case ExpressionType.Add:
                resultNumeric =
                    (int)dictionary["Numeric"] +
                    (int)((DynamicNumber)arg).dictionary["Numeric"];
                break;

            // Processing mathematical substraction (a - b).
            case ExpressionType.Subtract:
                resultNumeric =
                    (int)dictionary["Numeric"] -
                    (int)((DynamicNumber)arg).dictionary["Numeric"];
                break;

            // In case of any other binary operation,
            // print out the type of operation and return false,
            // which means that the language should determine
            // what to do.
            // (Usually the language just throws an exception.)
            default:
                Console.WriteLine(
                    binder.Operation +
                    ": This binary operation is not implemented");
                result = null;
                return false;
        }

        dynamic finalResult = new DynamicNumber();
        finalResult.Textual = resultTextual;
        finalResult.Numeric = resultNumeric;
        result = finalResult;
        return true;
    }
}

class Program
{
    static void Test(string[] args)
    {
        // Creating the first dynamic number.
        dynamic firstNumber = new DynamicNumber();

        // Creating properties and setting their values
        // for the first dynamic number.
        // The TrySetMember method is called.
        firstNumber.Textual = "One";
        firstNumber.Numeric = 1;

        // Printing out properties. The TryGetMember method is called.
        Console.WriteLine(
            firstNumber.Textual + " " + firstNumber.Numeric);

        // Creating the second dynamic number.
        dynamic secondNumber = new DynamicNumber();
        secondNumber.Textual = "Two";
        secondNumber.Numeric = 2;
        Console.WriteLine(
            secondNumber.Textual + " " + secondNumber.Numeric);

        dynamic resultNumber = new DynamicNumber();

        // Adding two numbers. The TryBinaryOperation is called.
        resultNumber = firstNumber + secondNumber;

        Console.WriteLine(
            resultNumber.Textual + " " + resultNumber.Numeric);

        // Subtracting two numbers. TryBinaryOperation is called.
        resultNumber = firstNumber - secondNumber;

        Console.WriteLine(
            resultNumber.Textual + " " + resultNumber.Numeric);

        // The following statement produces a run-time exception
        // because the multiplication operation is not implemented.
        // resultNumber = firstNumber * secondNumber;
    }
}

// This code example produces the following output:

// One 1
// Two 2
// One Add Two 3
// One Subtract Two -1

' Add Imports System.Linq.Expressions
' to the beginning of the file.
' The class derived from DynamicObject.
Public Class DynamicNumber
    Inherits DynamicObject

    ' The inner dictionary to store field names and values.
    Dim dictionary As New Dictionary(Of String, Object)

    ' Get the property value.
    Public Overrides Function TryGetMember(
        ByVal binder As System.Dynamic.GetMemberBinder,
        ByRef result As Object) As Boolean

        Return dictionary.TryGetValue(binder.Name, result)

    End Function

    ' Set the property value.
    Public Overrides Function TrySetMember(
        ByVal binder As System.Dynamic.SetMemberBinder,
        ByVal value As Object) As Boolean

        dictionary(binder.Name) = value
        Return True

    End Function

    ' Perform the binary operation. 
    Public Overrides Function TryBinaryOperation(
        ByVal binder As System.Dynamic.BinaryOperationBinder,
        ByVal arg As Object, ByRef result As Object) As Boolean

        ' The Textual property contains the textual representaion 
        ' of two numbers, in addition to the name of the binary operation.
        Dim resultTextual As String =
            dictionary("Textual") & " " &
            binder.Operation.ToString() & " " &
        CType(arg, DynamicNumber).dictionary("Textual")

        Dim resultNumeric As Integer

        ' Checking what type of operation is being performed.
        Select Case binder.Operation
            ' Proccessing mathematical addition (a + b).
            Case ExpressionType.Add
                resultNumeric =
                CInt(dictionary("Numeric")) +
                CInt((CType(arg, DynamicNumber)).dictionary("Numeric"))

                ' Processing mathematical substraction (a - b).
            Case ExpressionType.Subtract
                resultNumeric =
                CInt(dictionary("Numeric")) -
                CInt((CType(arg, DynamicNumber)).dictionary("Numeric"))

            Case Else
                ' In case of any other binary operation,
                ' print out the type of operation and return false,
                ' which means that the language should determine 
                ' what to do.
                ' (Usually the language just throws an exception.)
                Console.WriteLine(
                    binder.Operation.ToString() &
                    ": This binary operation is not implemented")
                result = Nothing
                Return False
        End Select

        Dim finalResult As Object = New DynamicNumber()
        finalResult.Textual = resultTextual
        finalResult.Numeric = resultNumeric
        result = finalResult
        Return True
    End Function
End Class

Sub Test()
    ' Creating the first dynamic number.
    Dim firstNumber As Object = New DynamicNumber()

    ' Creating properties and setting their values
    ' for the first dynamic number. 
    ' The TrySetMember method is called.
    firstNumber.Textual = "One"
    firstNumber.Numeric = 1

    ' Printing out properties. The TryGetMember method is called.
    Console.WriteLine(
        firstNumber.Textual & " " & firstNumber.Numeric)

    ' Creating the second dynamic number.
    Dim secondNumber As Object = New DynamicNumber()
    secondNumber.Textual = "Two"
    secondNumber.Numeric = 2
    Console.WriteLine(
        secondNumber.Textual & " " & secondNumber.Numeric)

    Dim resultNumber As Object = New DynamicNumber()

    ' Adding two numbers. TryBinaryOperation is called.
    resultNumber = firstNumber + secondNumber
    Console.WriteLine(
        resultNumber.Textual & " " & resultNumber.Numeric)

    ' Subtracting two numbers. TryBinaryOperation is called.
    resultNumber = firstNumber - secondNumber
    Console.WriteLine(
        resultNumber.Textual & " " & resultNumber.Numeric)

    ' The following statement produces a run-time exception
    ' because the multiplication operation is not implemented.
    ' resultNumber = firstNumber * secondNumber
End Sub

' This code example produces the following output:

' One 1
' Two 2
' One Add Two 3
' One Subtract Two -1

備註

衍生自 類別的 DynamicObject 類別可以覆寫這個方法，以指定動態物件應如何執行二進位作業。 未覆寫方法時，語言的執行時間系結器會決定行為。 (在大多數情況下，將會擲回特定語言的執行階段例外狀況)。

當您有加法或乘法等二進位運算時，就會呼叫這個方法。 例如，如果 TryBinaryOperation 覆寫 方法，系統會自動針對 或 multiply = first*second 之類的 sum = first + second 語句叫用此方法，其中 first 衍生自 DynamicObject 類別。

您可以使用 參數的 binder 屬性，取得二進位作業 Operation 類型的相關資訊。

如果您的動態物件只用于 C# 和 Visual Basic 中， binder.Operation 則 屬性可以從 列舉中取得下列其中一個值 ExpressionType 。 不過，在 IronPython 或 IronRuby 等其他語言中，您可以有其他值。

值	描述	C#	Visual Basic
Add	數值運算元沒有溢位檢查的加法運算。	a + b	a + b
AddAssign	數值運算元沒有溢位檢查的加法複合指派運算。	a += b	不支援。
And	位 AND 運算。	a & b	a And b
AndAssign	位 AND 複合指派作業。	a &= b	不支援。
Divide	算術除法運算。	a / b	a / b
DivideAssign	算術除法複合指派運算。	a /= b	不支援。
ExclusiveOr	位 XOR 運算。	a ^ b	a Xor b
ExclusiveOrAssign	位 XOR 複合指派作業。	a ^= b	不支援。
GreaterThan	「大於」比較。	a > b	a > b
GreaterThanOrEqual	「大於或等於」比較。	a >= b	不支援。
LeftShift	位左移運算。	a << b	a << b
LeftShiftAssign	位左移複合指派作業。	a <<= b	不支援。
LessThan	「小於」比較。	a < b	a < b
LessThanOrEqual	「小於或等於」比較。	a <= b	不支援。
Modulo	算術餘數運算。	a % b	a Mod b
ModuloAssign	算術餘數複合指派運算。	a %= b	不支援。
Multiply	數值運算元的乘法運算，不含溢位檢查。	a * b	a * b
MultiplyAssign	數值運算元的乘法複合指派運算，不含溢位檢查。	a *= b	不支援。
NotEqual	不等比較。	a != b	a <> b
Or	位或邏輯 OR 運算。	a &#124; b	a Or b
OrAssign	位或邏輯 OR 複合指派。	a &#124;= b	不支援。
Power	將數位提升為乘冪的數學運算。	不支援。	a ^ b
RightShift	位右移運算。	a >> b	a >> b
RightShiftAssign	位右移複合指派作業。	a >>= b	不支援。
Subtract	數值運算元沒有溢位檢查的減法運算。	a - b	a - b
SubtractAssign	數值運算元沒有溢位檢查的減法複合指派運算。	a -= b	不支援。

注意

若要在 C# 中實 OrElse 作動態物件的 (a || b) 和 AndAlso (a && b) 作業，您可以同時實 TryUnaryOperation 作 方法和 TryBinaryOperation 方法。

此 OrElse 作業是由一元 IsTrue 運算和二進位 Or 運算所組成。 Or只有在作業的結果 IsTrue 為 false 時，才會執行作業。

此 AndAlso 作業是由一元 IsFalse 運算和二進位 And 運算所組成。 And只有在作業的結果 IsFalse 為 false 時，才會執行作業。