Export (0) Print
Expand All

DynamicObject.TryBinaryOperation Method

Provides implementation for binary operations. Classes derived from the DynamicObject class can override this method to specify dynamic behavior for operations such as addition and multiplication.

Namespace:  System.Dynamic
Assembly:  System.Core (in System.Core.dll)

public virtual bool TryBinaryOperation(
	BinaryOperationBinder binder,
	Object arg,
	out Object result
)

Parameters

binder
Type: System.Dynamic.BinaryOperationBinder

Provides information about the binary operation. The binder.Operation property returns an ExpressionType object. For example, for the sum = first + second statement, where first and second are derived from the DynamicObject class, binder.Operation returns ExpressionType.Add.

arg
Type: System.Object

The right operand for the binary operation. For example, for the sum = first + second statement, where first and second are derived from the DynamicObject class, arg is equal to second.

result
Type: System.Object

The result of the binary operation.

Return Value

Type: System.Boolean
true if the operation is successful; otherwise, false. If this method returns false, the run-time binder of the language determines the behavior. (In most cases, a language-specific run-time exception is thrown.)

Classes derived from the DynamicObject class can override this method to specify how binary operations should be performed for a dynamic object. When the method is not overridden, the run-time binder of the language determines the behavior. (In most cases, a language-specific run-time exception is thrown.)

This method is called when you have binary operations such as addition or multiplication. For example, if the TryBinaryOperation method is overridden, it is automatically invoked for statements like sum = first + second or multiply = first*second, where first is derived from the DynamicObject class.

You can get information about the type of the binary operation by using the Operation property of the binder parameter.

If your dynamic object is used only in C# and Visual Basic, the binder.Operation property can have one of the following values from the ExpressionType enumeration. However, in other languages such as IronPython or IronRuby, you can have other values. For more information about ExpressionType, see documentation on the CodePlex Web site.

Value

Description

C#

Visual Basic

Add

An addition operation without overflow checking, for numeric operands.

a + b

a + b

AddAssign

An addition compound assignment operation without overflow checking, for numeric operands.

a += b

Not supported.

And

A bitwise AND operation.

a & b

a And b

AndAssign

A bitwise AND compound assignment operation.

a &= b

Not supported.

Divide

An arithmetic division operation.

a / b

a / b

DivideAssign

An arithmetic division compound assignment operation.

a /= b

Not supported.

ExclusiveOr

A bitwise XOR operation.

a ^ b

a Xor b

ExclusiveOrAssign

A bitwise XOR compound assignment operation.

a ^= b

Not supported.

GreaterThan

A "greater than" comparison.

a > b

a > b

GreaterThanOrEqual

A "greater than or equal to" comparison.

a >= b

Not supported.

LeftShift

A bitwise left-shift operation.

a << b

a << b

LeftShiftAssign

A bitwise left-shift compound assignment operation.

a <<= b

Not supported.

LessThan

A "less than" comparison.

a < b

a < b

LessThanOrEqual

A "less than or equal to" comparison.

a <= b

Not supported.

Modulo

An arithmetic remainder operation.

a % b

a Mod b

ModuloAssign

An arithmetic remainder compound assignment operation.

a %= b

Not supported.

Multiply

A multiplication operation without overflow checking, for numeric operands.

a * b

a * b

MultiplyAssign

A multiplication compound assignment operation without overflow checking, for numeric operands.

a *= b

Not supported.

NotEqual

An inequality comparison.

a != b

a <> b

Or

A bitwise or logical OR operation.

a | b

a Or b

OrAssign

A bitwise or logical OR compound assignment.

a |= b

Not supported.

Power

A mathematical operation of raising a number to a power.

Not supported.

a ^ b

RightShift

A bitwise right-shift operation.

a >> b

a >> b

RightShiftAssign

A bitwise right-shift compound assignment operation.

a >>= b

Not supported.

Subtract

A subtraction operation without overflow checking, for numeric operands.

a - b

a - b

SubtractAssign

A subtraction compound assignment operation without overflow checking, for numeric operands.

a -= b

Not supported.

NoteNote

To implement OrElse (a || b) and AndAlso (a && b) operations for dynamic objects in C#, you may want to implement both the TryUnaryOperation method and the TryBinaryOperation method.

The OrElse operation consists of the unary IsTrue operation and the binary Or operation. The Or operation is performed only if the result of the IsTrue operation is false.

The AndAlso operation consists of the unary IsFalse operation and the binary And operation. The And operation is performed only if the result of the IsFalse operation is false.

Assume that you need a data structure to store textual and numeric representations of numbers, and you want to define basic mathematical operations such as addition and subtraction for such data.

The following code example demonstrates the DynamicNumber class, which is derived from the DynamicObject class. DynamicNumber overrides the TryBinaryOperation method to enable mathematical operations. It also overrides the TrySetMember and TryGetMember methods to enable access to the elements.

In this example, only addition and subtraction operations are supported. If you try to write a statement like resultNumber = firstNumber*secondNumber, a run-time exception is thrown.

// 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

.NET Framework

Supported in: 4.5.2, 4.5.1, 4.5, 4

.NET Framework Client Profile

Supported in: 4

Portable Class Library

Supported in: Portable Class Library

.NET for Windows Store apps

Supported in: Windows 8

.NET for Windows Phone apps

Supported in: Windows Phone 8.1, Windows Phone 8, Silverlight 8.1

Windows Phone 8.1, Windows Phone 8, Windows 8.1, Windows Server 2012 R2, Windows 8, Windows Server 2012, Windows 7, Windows Vista SP2, Windows Server 2008 (Server Core Role not supported), Windows Server 2008 R2 (Server Core Role supported with SP1 or later; Itanium not supported)

The .NET Framework does not support all versions of every platform. For a list of the supported versions, see .NET Framework System Requirements.

Show:
© 2014 Microsoft