BlockExpression Class
Represents a block that contains a sequence of expressions where variables can be defined.
Assembly: System.Core (in System.Core.dll)
| Name | Description | |
|---|---|---|
![]() | CanReduce | Indicates that the node can be reduced to a simpler node. If this returns true, Reduce() can be called to produce the reduced form.(Inherited from Expression.) |
![]() | Expressions | Gets the expressions in this block. |
![]() | NodeType | Returns the node type of this expression. Extension nodes should return Extension when overriding this method.(Overrides Expression.NodeType.) |
![]() | Result | Gets the last expression in this block. |
![]() | Type | Gets the static type of the expression that this Expression represents.(Overrides Expression.Type.) |
![]() | Variables | Gets the variables defined in this block. |
| Name | Description | |
|---|---|---|
![]() | Accept(ExpressionVisitor) | Dispatches to the specific visit method for this node type. For example, MethodCallExpression calls the VisitMethodCall.(Overrides Expression.Accept(ExpressionVisitor).) |
![]() | Equals(Object) | Determines whether the specified object is equal to the current object.(Inherited from Object.) |
![]() | Finalize() | Allows an object to try to free resources and perform other cleanup operations before it is reclaimed by garbage collection.(Inherited from Object.) |
![]() | GetHashCode() | Serves as the default hash function. (Inherited from Object.) |
![]() | GetType() | |
![]() | MemberwiseClone() | |
![]() | Reduce() | Reduces this node to a simpler expression. If CanReduce returns true, this should return a valid expression. This method can return another node which itself must be reduced.(Inherited from Expression.) |
![]() | ReduceAndCheck() | Reduces this node to a simpler expression. If CanReduce returns true, this should return a valid expression. This method can return another node which itself must be reduced.(Inherited from Expression.) |
![]() | ReduceExtensions() | Reduces the expression to a known node type (that is not an Extension node) or just returns the expression if it is already a known type.(Inherited from Expression.) |
![]() | ToString() | Returns a textual representation of the Expression.(Inherited from Expression.) |
![]() | Update(IEnumerable(Of ParameterExpression), IEnumerable(Of Expression)) | Creates a new expression that is like this one, but using the supplied children. If all of the children are the same, it will return this expression. |
![]() | VisitChildren(ExpressionVisitor) | Reduces the node and then calls the visitor delegate on the reduced expression. The method throws an exception if the node is not reducible.(Inherited from Expression.) |
The following code example shows how to create a block expression. The block expression consists of two MethodCallExpression objects and one ConstantExpression object.
' Add the following directive to your file: ' Imports System.Linq.Expressions ' The block expression enables you to execute several expressions sequentually. ' When the block expression is executed, ' it returns the value of the last expression in the sequence. Dim blockExpr As BlockExpression = Expression.Block( Expression.Call( Nothing, GetType(Console).GetMethod("Write", New Type() {GetType(String)}), Expression.Constant("Hello ") ), Expression.Call( Nothing, GetType(Console).GetMethod("WriteLine", New Type() {GetType(String)}), Expression.Constant("World!") ), Expression.Constant(42) ) Console.WriteLine("The result of executing the expression tree:") ' The following statement first creates an expression tree, ' then compiles it, and then executes it. Dim result = Expression.Lambda(Of Func(Of Integer))(blockExpr).Compile()() ' Print the expressions from the block expression. Console.WriteLine("The expressions from the block expression:") For Each expr In blockExpr.Expressions Console.WriteLine(expr.ToString()) Next ' Print the result of the tree execution. Console.WriteLine("The return value of the block expression:") Console.WriteLine(result) ' This code example produces the following output: ' ' The result of executing the expression tree: ' Hello World! ' The expressions from the block expression: ' Write("Hello ") ' WriteLine("World!") ' 42 ' The return value of the block expression: ' 42
Available since 8
.NET Framework
Available since 4.0
Portable Class Library
Supported in: portable .NET platforms
Silverlight
Available since 4.0
Windows Phone Silverlight
Available since 8.0
Windows Phone
Available since 8.1
Any public static ( Shared in Visual Basic) members of this type are thread safe. Any instance members are not guaranteed to be thread safe.


