Expression.Assign(Expression, Expression) Metod

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

Parametrar

Returer

En BinaryExpression som har egenskapen NodeType lika med Assign och Left egenskaperna och Right inställda på de angivna värdena.

Exempel

I följande kodexempel visas hur du skapar ett uttryck som representerar en tilldelningsåtgärd.

// 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!

Kommentarer

Uttrycket Assign kopierar ett värde för värdetyper och kopierar en referens för referenstyper.