Expression.Return 方法

定義

命名空間:

System.Linq.Expressions

組件:

System.Linq.Expressions.dll

建立 GotoExpression，表示 return 陳述式。

多載

Return(LabelTarget)	建立 GotoExpression，表示 return 陳述式。
Return(LabelTarget, Expression)	建立 GotoExpression，表示 return 陳述式。 可以指定跳躍時傳遞至標籤的值。
Return(LabelTarget, Type)	建立 GotoExpression，表示含指定之類型的 return 陳述式。
Return(LabelTarget, Expression, Type)	建立 GotoExpression，表示含指定之類型的 return 陳述式。 可以指定跳躍時傳遞至標籤的值。

Return(LabelTarget)

來源:

GotoExpression.cs

建立 GotoExpression，表示 return 陳述式。

public:
 static System::Linq::Expressions::GotoExpression ^ Return(System::Linq::Expressions::LabelTarget ^ target);

public static System.Linq.Expressions.GotoExpression Return (System.Linq.Expressions.LabelTarget target);

static member Return : System.Linq.Expressions.LabelTarget -> System.Linq.Expressions.GotoExpression

Public Shared Function Return (target As LabelTarget) As GotoExpression

參數

target

LabelTarget

LabelTarget 將跳躍的目標 GotoExpression。

傳回

GotoExpression

GotoExpression，其 Kind 等於 Return、Target 屬性設定為 target，且包含在跳躍時傳遞至目標標籤的 Null 值。

Return(LabelTarget, Expression)

來源:

GotoExpression.cs

建立 GotoExpression，表示 return 陳述式。 可以指定跳躍時傳遞至標籤的值。

public:
 static System::Linq::Expressions::GotoExpression ^ Return(System::Linq::Expressions::LabelTarget ^ target, System::Linq::Expressions::Expression ^ value);

public static System.Linq.Expressions.GotoExpression Return (System.Linq.Expressions.LabelTarget target, System.Linq.Expressions.Expression? value);

static member Return : System.Linq.Expressions.LabelTarget * System.Linq.Expressions.Expression -> System.Linq.Expressions.GotoExpression

Public Shared Function Return (target As LabelTarget, value As Expression) As GotoExpression

參數

target

LabelTarget

LabelTarget 將跳躍的目標 GotoExpression。

value

Expression

將在跳躍時傳遞至關聯標籤的值。

傳回

GotoExpression

GotoExpression，其 Kind 等於 Continue、Target 屬性設定為 target，且，且包含在跳躍時傳遞至目標標籤的 value。

範例

下列範例示範如何建立包含 方法的 Return 表達式。

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

// A label expression of the void type that is the target for Expression.Return().
LabelTarget returnTarget = Expression.Label();

// This block contains a GotoExpression that represents a return statement with no value.
// It transfers execution to a label expression that is initialized with the same LabelTarget as the GotoExpression.
// The types of the GotoExpression, label expression, and LabelTarget must match.
BlockExpression blockExpr =
    Expression.Block(
        Expression.Call(typeof(Console).GetMethod("WriteLine", new Type[] { typeof(string) }), Expression.Constant("Return")),
        Expression.Return(returnTarget),
        Expression.Call(typeof(Console).GetMethod("WriteLine", new Type[] { typeof(string) }), Expression.Constant("Other Work")),
        Expression.Label(returnTarget)
    );

// The following statement first creates an expression tree,
// then compiles it, and then runs it.
Expression.Lambda<Action>(blockExpr).Compile()();

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

// "Other Work" is not printed because
// the Return expression transfers execution from Expression.Return(returnTarget)
// to Expression.Label(returnTarget).

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

' A label expression of the void type that is the target for Expression.Return().
Dim returnTarget As LabelTarget = Expression.Label()

' This block contains a GotoExpression that represents a return statement with no value.
' It transfers execution to a label expression that is initialized with the same LabelTarget as the GotoExpression.
' The types of the GotoExpression, label expression, and LabelTarget must match.
Dim blockExpr As BlockExpression =
      Expression.Block(
          Expression.Call(GetType(Console).GetMethod("WriteLine", New Type() {GetType(String)}), Expression.Constant("Return")),
          Expression.Return(returnTarget),
          Expression.Call(GetType(Console).GetMethod("WriteLine", New Type() {GetType(String)}), Expression.Constant("Other Work")),
          Expression.Label(returnTarget)
      )

' The following statement first creates an expression tree,
' then compiles it, and then runs it.
Expression.Lambda(Of Action)(blockExpr).Compile()()

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

' "Other Work" is not printed because 
' the Return expression transfers execution from Return(returnTarget)
' to Expression.Label(returnTarget).

Return(LabelTarget, Type)

來源:

GotoExpression.cs

建立 GotoExpression，表示含指定之類型的 return 陳述式。

public:
 static System::Linq::Expressions::GotoExpression ^ Return(System::Linq::Expressions::LabelTarget ^ target, Type ^ type);

public static System.Linq.Expressions.GotoExpression Return (System.Linq.Expressions.LabelTarget target, Type type);

static member Return : System.Linq.Expressions.LabelTarget * Type -> System.Linq.Expressions.GotoExpression

Public Shared Function Return (target As LabelTarget, type As Type) As GotoExpression

參數

target

LabelTarget

LabelTarget 將跳躍的目標 GotoExpression。

type

Type

要將 Type 屬性設定為與之相等的 Type。

傳回

GotoExpression

GotoExpression，其 Kind 等於 Return、Target 屬性設定為 target、Type 屬性設定為 type，且包含在跳躍時傳遞至目標標籤的 null 值。

Return(LabelTarget, Expression, Type)

來源:

GotoExpression.cs

建立 GotoExpression，表示含指定之類型的 return 陳述式。 可以指定跳躍時傳遞至標籤的值。

public:
 static System::Linq::Expressions::GotoExpression ^ Return(System::Linq::Expressions::LabelTarget ^ target, System::Linq::Expressions::Expression ^ value, Type ^ type);

public static System.Linq.Expressions.GotoExpression Return (System.Linq.Expressions.LabelTarget target, System.Linq.Expressions.Expression? value, Type type);

static member Return : System.Linq.Expressions.LabelTarget * System.Linq.Expressions.Expression * Type -> System.Linq.Expressions.GotoExpression

Public Shared Function Return (target As LabelTarget, value As Expression, type As Type) As GotoExpression

參數

target

LabelTarget

LabelTarget 將跳躍的目標 GotoExpression。

value

Expression

將在跳躍時傳遞至關聯標籤的值。

type

Type

要將 Type 屬性設定為與之相等的 Type。

傳回

GotoExpression

GotoExpression，其 Kind 等於Continue、Target 屬性設定為 target、Type 屬性設定為 type，且包含在跳躍時傳遞至目標標籤的 value。