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ExceptionHandlingClauseOptions Enumeration

Identifies kinds of exception-handling clauses.

This enumeration has a FlagsAttribute attribute that allows a bitwise combination of its member values.

Namespace:  System.Reflection
Assembly:  mscorlib (in mscorlib.dll)

[FlagsAttribute]
[ComVisibleAttribute(true)]
public enum class ExceptionHandlingClauseOptions

Member nameDescription
ClauseThe clause accepts all exceptions that derive from a specified type.
FaultThe clause is executed if an exception occurs, but not on completion of normal control flow.
FilterThe clause contains user-specified instructions that determine whether the exception should be ignored (that is, whether normal execution should resume), be handled by the associated handler, or be passed on to the next clause.
FinallyThe clause is executed whenever the try block exits, whether through normal control flow or because of an unhandled exception.

To examine the exception-handling clauses in a method, obtain a MethodInfo object and call the GetMethodBody method to obtain the method body. Use the ExceptionHandlingClauses property to obtain a list of ExceptionHandlingClause objects.

NoteNote

Working with exception-handling clauses requires a thorough understanding of metadata and Microsoft intermediate language (MSIL) instruction formats. Information can be found in the Common Language Infrastructure (CLI) documentation, especially "Partition II: Metadata Definition and Semantics" and "Partition III: CIL Instruction Set". The documentation is available online; see ECMA C# and Common Language Infrastructure Standards on MSDN and Standard ECMA-335 - Common Language Infrastructure (CLI) on the Ecma International Web site.

The following code example defines a test method named MethodBodyExample, and displays its local variable information and exception-handling clauses. The MethodBase::GetMethodBody method is used to obtain a MethodBody object for the test method. The ExceptionHandlingClauses property is used to obtain a list of ExceptionHandlingClause objects and display their properties.

NoteNote

Not all computer languages can generate ExceptionHandlingClauseOptions::Filter clauses. The Visual Basic example shows a filter clause, using a Visual Basic When expression, which is omitted from the examples for other languages.

This code is part of a larger example provided for the MethodBody class.

#using <System.dll>

using namespace System;
using namespace System::Reflection;

public ref class Example
{
    // The Main method contains code to analyze this method, using 
    // the properties and methods of the MethodBody class. 
public:
    void MethodBodyExample(Object^ arg)
    {
        // Define some local variables. In addition to these variables, 
        // the local variable list includes the variables scoped to  
        // the catch clauses. 
        int var1 = 42;
        String^ var2 = "Forty-two";

        try
        {
            // Depending on the input value, throw an ArgumentException or  
            // an ArgumentNullException to test the Catch clauses. 
            if (arg == nullptr)
            {
                throw gcnew ArgumentNullException("The argument cannot " +
                    "be null.");
            }
            if (arg->GetType() == String::typeid)
            {
                throw gcnew ArgumentException("The argument cannot " + 
                    "be a string.");
            }        
        }

        // There is no Filter clause in this code example. See the Visual  
        // Basic code for an example of a Filter clause. 

        // This catch clause handles the ArgumentException class, and 
        // any other class derived from Exception. 
        catch (ArgumentException^ ex)
        {
            Console::WriteLine("Ordinary exception-handling clause caught:" +
                " {0}", ex->GetType());
        }        
        finally
        {
            var1 = 3033;
            var2 = "Another string.";
        }
    }
};

int main()
{ 
    // Get method body information.
    MethodInfo^ mi = 
        Example::typeid->GetMethod("MethodBodyExample");

    MethodBody^ mb = mi->GetMethodBody();
    Console::WriteLine("\r\nMethod: {0}", mi);

    // Display the general information included in the  
    // MethodBody object.
    Console::WriteLine("    Local variables are initialized: {0}", 
        mb->InitLocals);
    Console::WriteLine("    Maximum number of items on the operand " +
        "stack: {0}", mb->MaxStackSize);


...



// Display exception handling clauses.
Console::WriteLine();
for each(ExceptionHandlingClause^ exhc in mb->ExceptionHandlingClauses)
{
    Console::WriteLine(exhc->Flags.ToString());

    // The FilterOffset property is meaningful only for Filter 
    // clauses. The CatchType property is not meaningful for  
    // Filter or Finally clauses.  
    switch(exhc->Flags)
    {
    case ExceptionHandlingClauseOptions::Filter:
        Console::WriteLine("        Filter Offset: {0}", 
            exhc->FilterOffset);
        break;
    case ExceptionHandlingClauseOptions::Finally:
        break;
    default:
        Console::WriteLine("    Type of exception: {0}", 
            exhc->CatchType);
        break;
    }

    Console::WriteLine("       Handler Length: {0}",
        exhc->HandlerLength);
    Console::WriteLine("       Handler Offset: {0}", 
        exhc->HandlerOffset);
    Console::WriteLine("     Try Block Length: {0}", exhc->TryLength);
    Console::WriteLine("     Try Block Offset: {0}", exhc->TryOffset);
}


...


    // The Main method contains code to analyze this method, using 
    // the properties and methods of the MethodBody class. 
public:
    void MethodBodyExample(Object^ arg)
    {
        // Define some local variables. In addition to these variables, 
        // the local variable list includes the variables scoped to  
        // the catch clauses. 
        int var1 = 42;
        String^ var2 = "Forty-two";

        try
        {
            // Depending on the input value, throw an ArgumentException or  
            // an ArgumentNullException to test the Catch clauses. 
            if (arg == nullptr)
            {
                throw gcnew ArgumentNullException("The argument cannot " +
                    "be null.");
            }
            if (arg->GetType() == String::typeid)
            {
                throw gcnew ArgumentException("The argument cannot " + 
                    "be a string.");
            }        
        }

        // There is no Filter clause in this code example. See the Visual  
        // Basic code for an example of a Filter clause. 

        // This catch clause handles the ArgumentException class, and 
        // any other class derived from Exception. 
        catch (ArgumentException^ ex)
        {
            Console::WriteLine("Ordinary exception-handling clause caught:" +
                " {0}", ex->GetType());
        }        
        finally
        {
            var1 = 3033;
            var2 = "Another string.";
        }
    }


...


//Clause 
//    Type of exception: System.ArgumentException 
//       Handler Length: 29 
//       Handler Offset: 78 
//     Try Block Length: 65 
//     Try Block Offset: 13 
//Finally 
//       Handler Length: 13 
//       Handler Offset: 113 
//     Try Block Length: 100 
//     Try Block Offset: 13

.NET Framework

Supported in: 4.6, 4.5, 4, 3.5, 3.0, 2.0

.NET Framework Client Profile

Supported in: 4, 3.5 SP1
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