Expression.Return 方法
定義
重要
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建立 GotoExpression 一個代表返回語句的表示。
多載
| 名稱 | Description |
|---|---|
| Return(LabelTarget) |
建立 GotoExpression 一個代表返回語句的表示。 |
| Return(LabelTarget, Expression) |
建立 GotoExpression 一個代表返回語句的表示。 跳躍時傳遞給標籤的值可以指定。 |
| Return(LabelTarget, Type) |
建立 GotoExpression 一個代表指定型別的回傳語句。 |
| Return(LabelTarget, Expression, Type) |
建立 GotoExpression 一個代表指定型別的回傳語句。 跳躍時傳遞給標籤的值可以指定。 |
Return(LabelTarget)
建立 GotoExpression 一個代表返回語句的表示。
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他們會跳到那GotoExpression個地方。
傳回
GotoExpression一個等Kind於 Return,Target屬性設為 target,跳躍時要傳遞一個空值給目標標籤。
適用於
Return(LabelTarget, Expression)
建立 GotoExpression 一個代表返回語句的表示。 跳躍時傳遞給標籤的值可以指定。
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);
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他們會跳到那GotoExpression個地方。
- value
- Expression
跳轉時會傳遞給相關標籤的值。
傳回
GotoExpression A 等Kind於 Continue,Target將屬性設為 target,跳value躍時傳遞給目標標籤。
範例
以下範例示範如何建立包含該 Return 方法的表達式。
// 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).
適用於
Return(LabelTarget, Type)
建立 GotoExpression 一個代表指定型別的回傳語句。
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他們會跳到那GotoExpression個地方。
傳回
A GotoExpression 中 Kind 等於 Return, Target 屬性設 target為 , Type 屬性設為 type,跳躍時傳送一個空值。
適用於
Return(LabelTarget, Expression, Type)
建立 GotoExpression 一個代表指定型別的回傳語句。 跳躍時傳遞給標籤的值可以指定。
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);
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他們會跳到那GotoExpression個地方。
- value
- Expression
跳轉時會傳遞給相關標籤的值。
傳回
GotoExpression A 等Kind於 Continue,Target屬性設target為 ,屬性設為 ,Type屬性設為 type,value跳躍時傳給目標標籤。