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TryExpression Class

Represents a try/catch/finally/fault block.

System.Object
  System.Linq.Expressions.Expression
    System.Linq.Expressions.TryExpression

Namespace:  System.Linq.Expressions
Assembly:  System.Core (in System.Core.dll)

public sealed class TryExpression : Expression

The TryExpression type exposes the following members.

  NameDescription
Public propertyBodyGets the Expression representing the body of the try block.
Public propertyCanReduceIndicates 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.)
Public propertyFaultGets the Expression representing the fault block.
Public propertyFinallyGets the Expression representing the finally block.
Public propertyHandlersGets the collection of CatchBlock expressions associated with the try block.
Public propertyNodeTypeReturns the node type of this Expression. (Overrides Expression.NodeType.)
Public propertyTypeGets the static type of the expression that this Expression represents. (Overrides Expression.Type.)
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  NameDescription
Protected methodAcceptDispatches to the specific visit method for this node type. For example, MethodCallExpression calls the VisitMethodCall. (Inherited from Expression.)
Public methodEquals(Object)Determines whether the specified Object is equal to the current Object. (Inherited from Object.)
Protected methodFinalizeAllows an object to try to free resources and perform other cleanup operations before the Object is reclaimed by garbage collection. (Inherited from Object.)
Public methodGetHashCodeServes as a hash function for a particular type. (Inherited from Object.)
Public methodGetTypeGets the Type of the current instance. (Inherited from Object.)
Protected methodMemberwiseCloneCreates a shallow copy of the current Object. (Inherited from Object.)
Public methodReduceReduces 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.)
Public methodReduceAndCheckReduces 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.)
Public methodReduceExtensionsReduces 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.)
Public methodToStringReturns a textual representation of the Expression. (Inherited from Expression.)
Public methodUpdateCreates 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.
Protected methodVisitChildrenReduces 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.)
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The body block is protected by the try block.

The handlers consist of a set of CatchBlock expressions that can be either catch statements or filters.

The fault block runs if an exception is thrown.

The finally block runs regardless of how control exits the body.

Only one of fault or finally blocks can be supplied.

The return type of the try block must match the return type of any associated catch statements.

The following example demonstrates how to create a TryExpression object that contains a catch statement by using the TryCatch method.


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

// A TryExpression object that has a Catch statement.
// The return types of the Try block and all Catch blocks must be the same.
TryExpression tryCatchExpr =
    Expression.TryCatch(
        Expression.Block(
            Expression.Throw(Expression.Constant(new DivideByZeroException())),
            Expression.Constant("Try block")
        ),
        Expression.Catch(
            typeof(DivideByZeroException),
            Expression.Constant("Catch block")
        )
    );

// The following statement first creates an expression tree,
// then compiles it, and then runs it.
// If the exception is caught, 
// the result of the TryExpression is the last statement 
// of the corresponding Catch statement.
outputBlock.Text += Expression.Lambda<Func<string>>(tryCatchExpr).Compile()() + "\n";

// This code example produces the following output:
//
// Catch block


Silverlight

Supported in: 5, 4

For a list of the operating systems and browsers that are supported by Silverlight, see Supported Operating Systems and Browsers.

Any public static (Shared in Visual Basic) members of this type are thread safe. Any instance members are not guaranteed to be thread safe.

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