# DynamicObject.TryBinaryOperation Method

## Definition

Important

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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.

```
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`

#### Parameters

- binder
- 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
- 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
- Object

The result of the binary operation.

#### Returns

`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.)

## Examples

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
```

```
' 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
```

## Remarks

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.

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. |

Note

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`

.