Expression.Assign(Expression, Expression) Metode

Definisi

Ruang nama:

System.Linq.Expressions

Rakitan:

System.Linq.Expressions.dll

Sumber:

BinaryExpression.cs

Membuat yang BinaryExpression mewakili operasi penugasan.

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

Parameter

left

Expression

Untuk Expression mengatur properti sama Left dengan.

right

Expression

Untuk Expression mengatur properti sama Right dengan.

Mengembalikan

BinaryExpression

BinaryExpression yang memiliki NodeType properti yang sama dengan Assign dan Left properti dan Right diatur ke nilai yang ditentukan.

Contoh

Contoh kode berikut menunjukkan cara membuat ekspresi yang mewakili operasi penugasan.

// 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!

Keterangan

Assign Ekspresi menyalin nilai untuk jenis nilai, dan menyalin referensi untuk jenis referensi.