DynamicObject.TryUnaryOperation(UnaryOperationBinder, Object) Metode

Definisi

Ruang nama:

System.Dynamic

Rakitan:

System.Linq.Expressions.dll

Sumber:

DynamicObject.cs

Menyediakan implementasi untuk operasi unary. Kelas yang berasal dari DynamicObject kelas dapat mengambil alih metode ini untuk menentukan perilaku dinamis untuk operasi seperti negasi, kenaikan, atau penurunan.

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

public virtual bool TryUnaryOperation (System.Dynamic.UnaryOperationBinder binder, out object? result);

abstract member TryUnaryOperation : System.Dynamic.UnaryOperationBinder * obj -> bool
override this.TryUnaryOperation : System.Dynamic.UnaryOperationBinder * obj -> bool

Public Overridable Function TryUnaryOperation (binder As UnaryOperationBinder, ByRef result As Object) As Boolean

Parameter

binder

UnaryOperationBinder

Menyediakan informasi tentang operasi unary. Properti binder.Operation mengembalikan ExpressionType objek . Misalnya, untuk negativeNumber = -number pernyataan , di mana number berasal dari DynamicObject kelas , binder.Operation mengembalikan "Negate".

result

Object

Hasil dari operasi unary.

Mengembalikan

Boolean

true jika operasi berhasil; jika tidak, false. Jika metode ini mengembalikan false, pengikat run-time bahasa menentukan perilaku. (Dalam kebanyakan kasus, pengecualian run-time khusus bahasa dilemparkan.)

Contoh

Asumsikan bahwa Anda memerlukan struktur data untuk menyimpan representasi tekstual dan numerik angka, dan Anda ingin menentukan operasi negasi matematika untuk data tersebut.

Contoh kode berikut menunjukkan DynamicNumber kelas , yang berasal dari DynamicObject kelas . DynamicNumber mengambil TryUnaryOperation alih metode untuk mengaktifkan operasi negasi matematika. Juga mengambil alih TrySetMember metode dan TryGetMember untuk mengaktifkan akses ke elemen.

Dalam contoh ini, hanya operasi negasi matematika yang didukung. Jika Anda mencoba menulis pernyataan seperti negativeNumber = +number, pengecualian run-time terjadi.

// 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 unary operation.
    public override bool TryUnaryOperation(
        UnaryOperationBinder binder, out object result)
    {
        // The Textual property contains
        // the name of the unary operation in addition
        // to the textual representaion of the number.
        string resultTextual =
             binder.Operation + " " +
             dictionary["Textual"].ToString();
        int resultNumeric;

        // Determining what type of operation is being performed.
        switch (binder.Operation)
        {
            case ExpressionType.Negate:
                resultNumeric =
                     -(int)dictionary["Numeric"];
                break;
            default:
                // In case of any other unary 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 +
                    ": This unary 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 number = new DynamicNumber();

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

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

        dynamic negativeNumber = new DynamicNumber();

        // Performing a mathematical negation.
        // TryUnaryOperation is called.
        negativeNumber = -number;

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

        // The following statement produces a run-time exception
        // because the unary plus operation is not implemented.
        // negativeNumber = +number;
    }
}

// This code example produces the following output:

// One 1
// Negate One -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 unary operation. 
    Public Overrides Function TryUnaryOperation(
        ByVal binder As System.Dynamic.UnaryOperationBinder,
        ByRef result As Object) As Boolean

        ' The Textual property contains the name of the unary operation
        ' in addition to the textual representaion of the number.
        Dim resultTextual As String =
        binder.Operation.ToString() & " " &
        dictionary("Textual")
        Dim resultNumeric As Integer

        ' Determining what type of operation is being performed.
        Select Case binder.Operation
            Case ExpressionType.Negate
                resultNumeric = -CInt(dictionary("Numeric"))
            Case Else
                ' In case of any other unary 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 unary 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 number As Object = New DynamicNumber()

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

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

    Dim negativeNumber As Object = New DynamicNumber()

    ' Performing a mathematical negation.
    ' The TryUnaryOperation is called.
    negativeNumber = -number

    Console.WriteLine(
        negativeNumber.Textual & " " & negativeNumber.Numeric)

    ' The following statement produces a run-time exception
    ' because the unary plus operation is not implemented.
    'negativeNumber = +number
End Sub

' This code example produces the following output:

' One 1
' Negate One -1

Keterangan

Kelas yang berasal dari DynamicObject kelas dapat mengambil alih metode ini untuk menentukan bagaimana operasi unary harus dilakukan untuk objek dinamis. Ketika metode tidak ditimpa, pengikat run-time bahasa menentukan perilaku. (Dalam kebanyakan kasus, pengecualian run-time khusus bahasa dilemparkan.)

Metode ini dipanggil ketika Anda memiliki operasi unary seperti negasi, kenaikan, atau penurunan. Misalnya, jika TryUnaryOperation metode ditimpa, metode ini secara otomatis dipanggil untuk pernyataan seperti negativeNumber = -number, di mana number berasal dari DynamicObject kelas .

Anda bisa mendapatkan informasi tentang jenis operasi unary dengan menggunakan Operation properti binder parameter .

Jika objek dinamis Anda hanya digunakan di C# dan Visual Basic, binder.Operation properti dapat memiliki salah satu nilai berikut dari ExpressionType enumerasi. Namun, dalam bahasa lain seperti IronPython atau IronRuby, Anda dapat memiliki nilai lain.

Nilai	Deskripsi	C#	Visual Basic
Decrement	Operasi penurunan unary.	a--	Tidak didukung.
Increment	Operasi kenaikan unary.	a++	Tidak didukung.
Negate	Negasi aritmatika.	-a	-a
Not	Negasi logis.	!a	Not a
OnesComplement	Satu pelengkap.	~a	Tidak didukung.
IsFalse	Nilai kondisi palsu.	a && b	Tidak didukung.
IsTrue	Nilai kondisi yang benar.	a || b	Tidak didukung.
UnaryPlus	Nilai tambah unary.	+a	+a

Catatan

Untuk menerapkan OrElse operasi (a || b) dan AndAlso (a && b) untuk objek dinamis di C#, Anda mungkin ingin menerapkan TryUnaryOperation metode dan TryBinaryOperation metode .

Operasi ini OrElse terdiri dari operasi unary IsTrue dan operasi biner Or . Or Operasi dilakukan hanya jika hasil IsTrue operasi adalah false.

Operasi ini AndAlso terdiri dari operasi unary IsFalse dan operasi biner And . And Operasi dilakukan hanya jika hasil IsFalse operasi adalah false.