Expression.MemberInit 方法

定义

命名空间:

System.Linq.Expressions

程序集:

System.Linq.Expressions.dll

表示一个表达式，该表达式创建新对象并初始化该对象的一个属性。

重载

MemberInit(NewExpression, IEnumerable<MemberBinding>)	表示一个表达式，该表达式创建新对象并初始化该对象的一个属性。
MemberInit(NewExpression, MemberBinding[])	创建一个 MemberInitExpression。

MemberInit(NewExpression, IEnumerable<MemberBinding>)

Source:

MemberInitExpression.cs

表示一个表达式，该表达式创建新对象并初始化该对象的一个属性。

public:
 static System::Linq::Expressions::MemberInitExpression ^ MemberInit(System::Linq::Expressions::NewExpression ^ newExpression, System::Collections::Generic::IEnumerable<System::Linq::Expressions::MemberBinding ^> ^ bindings);

public static System.Linq.Expressions.MemberInitExpression MemberInit (System.Linq.Expressions.NewExpression newExpression, System.Collections.Generic.IEnumerable<System.Linq.Expressions.MemberBinding> bindings);

static member MemberInit : System.Linq.Expressions.NewExpression * seq<System.Linq.Expressions.MemberBinding> -> System.Linq.Expressions.MemberInitExpression

Public Shared Function MemberInit (newExpression As NewExpression, bindings As IEnumerable(Of MemberBinding)) As MemberInitExpression

参数

newExpression

NewExpression

要将 NewExpression 属性设置为与其相等的 NewExpression。

bindings

IEnumerable<MemberBinding>

一个 IEnumerable<T>，包含用来填充 MemberBinding 集合的 Bindings 对象。

返回

MemberInitExpression

一个 MemberInitExpression，其 NodeType 属性等于 MemberInit，并且其 NewExpression 和 Bindings 属性设置为指定值。

例外

ArgumentNullException

newExpression 或 bindings 为 null。

ArgumentException

bindings 的元素的 Member 属性不表示 newExpression.Type 所表示的类型的成员。

示例

以下示例演示一个表达式，该表达式创建新 对象并初始化 对象的属性。

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

class TestMemberInitClass
{
    public int sample { get; set; }
}

static void MemberInit()
{
    // This expression creates a new TestMemberInitClass object
    // and assigns 10 to its sample property.
    Expression testExpr = Expression.MemberInit(
        Expression.New(typeof(TestMemberInitClass)),
        new List<MemberBinding>() {
            Expression.Bind(typeof(TestMemberInitClass).GetMember("sample")[0], Expression.Constant(10))
        }
    );

    // The following statement first creates an expression tree,
    // then compiles it, and then runs it.
    var test = Expression.Lambda<Func<TestMemberInitClass>>(testExpr).Compile()();
    Console.WriteLine(test.sample);
}

// This code example produces the following output:
//
// 10

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

Class TestMemberInitClass
    Public Property Sample As Integer
End Class

Sub MemberInit()
    ' This expression creates a new TestMemberInitClass object
    ' and assigns 10 to its Sample property.
    Dim testExpr As Expression = Expression.MemberInit(
        Expression.[New](GetType(TestMemberInitClass)),
        New List(Of MemberBinding)() From {
            Expression.Bind(GetType(TestMemberInitClass).GetMember("Sample")(0), Expression.Constant(10))
        }
    )

    ' The following statement first creates an expression tree,
    ' then compiles it, and then runs it.
    Dim test = Expression.Lambda(Of Func(Of TestMemberInitClass))(testExpr).Compile()()
    Console.WriteLine(test.Sample)
End Sub

' This code example produces the following output:
'
' 10

注解

Type生成的 MemberInitExpression 的 属性等于 Type 的 newExpression属性。

MemberInit(NewExpression, MemberBinding[])

Source:

MemberInitExpression.cs

创建一个 MemberInitExpression。

public:
 static System::Linq::Expressions::MemberInitExpression ^ MemberInit(System::Linq::Expressions::NewExpression ^ newExpression, ... cli::array <System::Linq::Expressions::MemberBinding ^> ^ bindings);

public static System.Linq.Expressions.MemberInitExpression MemberInit (System.Linq.Expressions.NewExpression newExpression, params System.Linq.Expressions.MemberBinding[] bindings);

static member MemberInit : System.Linq.Expressions.NewExpression * System.Linq.Expressions.MemberBinding[] -> System.Linq.Expressions.MemberInitExpression

Public Shared Function MemberInit (newExpression As NewExpression, ParamArray bindings As MemberBinding()) As MemberInitExpression

参数

newExpression

NewExpression

要将 NewExpression 属性设置为与其相等的 NewExpression。

bindings

MemberBinding[]

用于填充 MemberBinding 集合的 Bindings 对象的数组。

返回

MemberInitExpression

一个 MemberInitExpression，其 NodeType 属性等于 MemberInit，并且其 NewExpression 和 Bindings 属性设置为指定值。

例外

ArgumentNullException

newExpression 或 bindings 为 null。

ArgumentException

bindings 的元素的 Member 属性不表示 newExpression.Type 所表示的类型的成员。

示例

下面的示例演示如何使用 MemberInit(NewExpression, MemberBinding[]) 方法创建表示 MemberInitExpression 新 对象的两个成员的初始化的 。

class Animal
{
    public string Species {get; set;}
    public int Age {get; set;}
}

public static void CreateMemberInitExpression()
{
    System.Linq.Expressions.NewExpression newAnimal =
        System.Linq.Expressions.Expression.New(typeof(Animal));

    System.Reflection.MemberInfo speciesMember =
        typeof(Animal).GetMember("Species")[0];
    System.Reflection.MemberInfo ageMember =
        typeof(Animal).GetMember("Age")[0];

    // Create a MemberBinding object for each member
    // that you want to initialize.
    System.Linq.Expressions.MemberBinding speciesMemberBinding =
        System.Linq.Expressions.Expression.Bind(
            speciesMember,
            System.Linq.Expressions.Expression.Constant("horse"));
    System.Linq.Expressions.MemberBinding ageMemberBinding =
        System.Linq.Expressions.Expression.Bind(
            ageMember,
            System.Linq.Expressions.Expression.Constant(12));

    // Create a MemberInitExpression that represents initializing
    // two members of the 'Animal' class.
    System.Linq.Expressions.MemberInitExpression memberInitExpression =
        System.Linq.Expressions.Expression.MemberInit(
            newAnimal,
            speciesMemberBinding,
            ageMemberBinding);

    Console.WriteLine(memberInitExpression.ToString());

    // This code produces the following output:
    //
    // new Animal() {Species = "horse", Age = 12}
}

Class Animal
    Public Species As String
    Public Age As Integer
End Class

Shared Sub CreateMemberInitExpression()
    Dim newAnimal As System.Linq.Expressions.NewExpression = _
        System.Linq.Expressions.Expression.[New](Type.GetType("ExpressionVB.MemberInitExample+Animal"))

    Dim speciesMember As System.Reflection.MemberInfo = _
        Type.GetType("ExpressionVB.MemberInitExample+Animal").GetMember("Species")(0)
    Dim ageMember As System.Reflection.MemberInfo = _
        Type.GetType("ExpressionVB.MemberInitExample+Animal").GetMember("Age")(0)

    ' Create a MemberBinding object for each member
    ' that you want to initialize.
    Dim speciesMemberBinding As System.Linq.Expressions.MemberBinding = _
        System.Linq.Expressions.Expression.Bind( _
            speciesMember, _
            System.Linq.Expressions.Expression.Constant("horse"))
    Dim ageMemberBinding As System.Linq.Expressions.MemberBinding = _
        System.Linq.Expressions.Expression.Bind( _
            ageMember, _
            System.Linq.Expressions.Expression.Constant(12))

    ' Create a MemberInitExpression that represents initializing
    ' two members of the 'Animal' class.
    Dim memberInitExpression As System.Linq.Expressions.MemberInitExpression = _
        System.Linq.Expressions.Expression.MemberInit( _
            newAnimal, _
            speciesMemberBinding, _
            ageMemberBinding)

    Console.WriteLine(memberInitExpression.ToString())

    ' This code produces the following output:
    '
    ' new Animal() {Species = "horse", Age = 12}
End Sub

注解

Type生成的 MemberInitExpression 的 属性等于 Type 的 newExpression属性。