Expression.Assign(Expression, Expression) Метод

Определение

Создает выражение BinaryExpression, представляющее операцию присваивания.Creates a BinaryExpression that represents an assignment operation.

public:
 static System::Linq::Expressions::BinaryExpression ^ Assign(System::Linq::Expressions::Expression ^ left, System::Linq::Expressions::Expression ^ right);
public static System.Linq.Expressions.BinaryExpression Assign (System.Linq.Expressions.Expression left, System.Linq.Expressions.Expression right);
static member Assign : System.Linq.Expressions.Expression * System.Linq.Expressions.Expression -> System.Linq.Expressions.BinaryExpression
Public Shared Function Assign (left As Expression, right As Expression) As BinaryExpression

Параметры

left
Expression

Объект Expression, который следует задать в качестве значения свойства Left.An Expression to set the Left property equal to.

right
Expression

Объект Expression, который следует задать в качестве значения свойства Right.An Expression to set the Right property equal to.

Возвраты

Выражение BinaryExpression со свойствомNodeType, равным Assign, и свойствами Left и Right, для которых заданы указанные значения.A BinaryExpression that has the NodeType property equal to Assign and the Left and Right properties set to the specified values.

Примеры

В следующем примере кода показано, как создать выражение, представляющее операцию присваивания.The following code example shows how to create an expression that represents an assignment operation.

// Add the following directive to your file:
// using System.Linq.Expressions;  

// To demonstrate the assignment operation, we create a variable.
ParameterExpression variableExpr = Expression.Variable(typeof(String), "sampleVar");

// This expression represents the assignment of a value
// to a variable expression.
// It copies a value for value types, and
// copies a reference for reference types.
Expression assignExpr = Expression.Assign(
    variableExpr,
    Expression.Constant("Hello World!")
    );

// The block expression allows for executing several expressions sequentually.
// In this block, we pass the variable expression as a parameter,
// and then assign this parameter a value in the assign expression.
Expression blockExpr = Expression.Block(
    new ParameterExpression[] { variableExpr },
    assignExpr
    );

// Print out the assign expression.
Console.WriteLine(assignExpr.ToString());

// The following statement first creates an expression tree,
// then compiles it, and then executes it.  
Console.WriteLine(Expression.Lambda<Func<String>>(blockExpr).Compile()());

// This code example produces the following output:
//
// (sampleVar = "Hello World!")
// Hello World!

' Add the following directive to your file:
' Imports System.Linq.Expressions 

' To demonstrate the assignment operation, create a variable.
Dim variableExpr As ParameterExpression = Expression.Variable(GetType(String), "sampleVar")

' This expression represents the assignment of a value
' to a variable expression.
' It copies a value for value types, and it
' copies a reference for reference types.
Dim assignExpr As Expression = Expression.Assign(
    variableExpr,
    Expression.Constant("Hello World!")
    )

' The block expression allows for executing several expressions sequentually.
' In this block, you pass the variable expression as a parameter,
' and then assign this parameter a value in the assign expression.
Dim blockExpr As Expression = Expression.Block(
      New ParameterExpression() {variableExpr}, assignExpr
      )

' Print the assign expression.
Console.WriteLine(assignExpr.ToString())

' The following statement first creates an expression tree,
' then compiles it, and then executes it. 
Console.WriteLine(Expression.Lambda(Of Func(Of String))(blockExpr).Compile()())

' This code example produces the following output:
'
' (sampleVar = "Hello World!")
' Hello World!

Комментарии

Assign Выражение копирует значение для типов значений и копирует ссылку для ссылочных типов.The Assign expression copies a value for value types, and it copies a reference for reference types.

Применяется к