DynamicObject.TryBinaryOperation Metoda

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);

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

Parametry

Návraty

truepokud je operace úspěšná; v opačném případě . false Pokud tato metoda vrátí false, pořadač běhu jazyka určuje chování. (Ve většině případů se vyvolá výjimka za běhu pro konkrétní jazyk.)

Příklady

Předpokládejme, že potřebujete datovou strukturu pro ukládání textových a číselných reprezentací čísel a chcete definovat základní matematické operace, jako je sčítání a odčítání pro taková data.

Následující příklad kódu ukazuje DynamicNumber třídu, která je odvozena z DynamicObject třídy . DynamicNumber přepisuje metodu TryBinaryOperation pro povolení matematických operací. Přepíše TrySetMember také metody a TryGetMember pro povolení přístupu k prvkům.

V tomto příkladu se podporují pouze operace sčítání a odčítání. Pokud se pokusíte napsat příkaz jako resultNumber = firstNumber*secondNumber, vyvolá se výjimka za běhu.

// 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

Poznámky

Třídy odvozené z DynamicObject třídy mohou přepsat tuto metodu a určit způsob provádění binárních operací pro dynamický objekt. Pokud metoda není přepsána, pořadač za běhu jazyka určuje chování. (Ve většině případů se vyvolá výjimka za běhu pro konkrétní jazyk.)

Tato metoda je volána, pokud máte binární operace, jako je sčítání nebo násobení. Pokud TryBinaryOperation je například metoda přepsána, je automaticky vyvolána pro příkazy jako sum = first + second nebo multiply = first*second, kde first je odvozen z DynamicObject třídy .

Informace o typu binární operace můžete získat pomocí Operation vlastnosti parametru binder .

Pokud je dynamický objekt použit pouze v jazyce C# a Visual Basic, binder.Operation vlastnost může mít jednu z následujících hodnot z výčtu ExpressionType . V jiných jazycích, jako je IronPython nebo IronRuby, ale můžete mít i jiné hodnoty.

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