ExceptionHandlingClause.HandlerLength Propriedade
Definição
Importante
Algumas informações se referem a produtos de pré-lançamento que podem ser substancialmente modificados antes do lançamento. A Microsoft não oferece garantias, expressas ou implícitas, das informações aqui fornecidas.
Obtém o comprimento, em bytes, do corpo dessa cláusula de tratamento de exceção.
public:
virtual property int HandlerLength { int get(); };
public:
property int HandlerLength { int get(); };
public virtual int HandlerLength { get; }
public int HandlerLength { get; }
member this.HandlerLength : int
Public Overridable ReadOnly Property HandlerLength As Integer
Public ReadOnly Property HandlerLength As Integer
Valor da propriedade
Um inteiro que representa o comprimento, em bytes, do MSIL que forma o corpo dessa cláusula de tratamento de exceção.
Exemplos
O exemplo de código a seguir define um método de teste chamado MethodBodyExample
e exibe suas informações de variável local e cláusulas de tratamento de exceção. O MethodBase.GetMethodBody método é usado para obter um MethodBody objeto para o método de teste. A ExceptionHandlingClauses propriedade é usada para obter uma lista de ExceptionHandlingClause objetos e exibir suas propriedades.
Esse código faz parte de um exemplo maior localizado no tópico de MethodBody classe.
#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);
using System;
using System.Reflection;
public class Example
{
public static void Main()
{
// Get method body information.
MethodInfo mi = typeof(Example).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);
Imports System.Reflection
Public Class Example
Public Shared Sub Main()
' Demonstrate the effect of the Visual Basic When keyword, which
' generates a Filter clause in the Try block.
Dim e As New Example()
Console.WriteLine()
e.MethodBodyExample("String argument")
e.MethodBodyExample(Nothing)
' Get method body information.
Dim mi As MethodInfo = _
GetType(Example).GetMethod("MethodBodyExample")
Dim mb As MethodBody = mi.GetMethodBody()
Console.WriteLine(vbCrLf & "Method: {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);
}
// Display exception handling clauses.
Console.WriteLine();
foreach (ExceptionHandlingClause ehc in mb.ExceptionHandlingClauses)
{
Console.WriteLine(ehc.Flags.ToString());
// The FilterOffset property is meaningful only for Filter
// clauses. The CatchType property is not meaningful for
// Filter or Finally clauses.
switch (ehc.Flags)
{
case ExceptionHandlingClauseOptions.Filter:
Console.WriteLine(" Filter Offset: {0}",
ehc.FilterOffset);
break;
case ExceptionHandlingClauseOptions.Finally:
break;
default:
Console.WriteLine(" Type of exception: {0}",
ehc.CatchType);
break;
}
Console.WriteLine(" Handler Length: {0}", ehc.HandlerLength);
Console.WriteLine(" Handler Offset: {0}", ehc.HandlerOffset);
Console.WriteLine(" Try Block Length: {0}", ehc.TryLength);
Console.WriteLine(" Try Block Offset: {0}", ehc.TryOffset);
}
' Display exception handling clauses.
Console.WriteLine()
For Each ehc As ExceptionHandlingClause In mb.ExceptionHandlingClauses
Console.WriteLine(ehc.Flags.ToString())
' The FilterOffset property is meaningful only for Filter
' clauses. The CatchType property is not meaningful for
' Filter or Finally clauses.
Select Case ehc.Flags
Case ExceptionHandlingClauseOptions.Filter
Console.WriteLine(" Filter Offset: {0}", _
ehc.FilterOffset)
Case ExceptionHandlingClauseOptions.Finally
Case Else
Console.WriteLine(" Type of exception: {0}", _
ehc.CatchType)
End Select
Console.WriteLine(" Handler Length: {0}", ehc.HandlerLength)
Console.WriteLine(" Handler Offset: {0}", ehc.HandlerOffset)
Console.WriteLine(" Try Block Length: {0}", ehc.TryLength)
Console.WriteLine(" Try Block Offset: {0}", ehc.TryOffset)
Next
// 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.";
}
}
}
// 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 == null)
{
throw new ArgumentNullException("The argument cannot be null.");
}
if (arg.GetType() == typeof(string))
{
throw new ArgumentException("The argument cannot be a string.");
}
}
// This filter clause selects only exceptions that derive
// from the ArgumentException class.
// Other exceptions, including ArgumentException itself,
// are not handled by this filter clause.
catch (ArgumentException ex) when (ex.GetType().IsSubclassOf(typeof(ArgumentException)))
{
Console.WriteLine("Filter clause caught: {0}", ex.GetType());
}
// This catch clause handles the ArgumentException class, and
// any other class derived from Exception.
catch(Exception ex)
{
Console.WriteLine("Ordinary exception-handling clause caught: {0}",
ex.GetType());
}
finally
{
var1 = 3033;
var2 = "Another string.";
}
}
}
// This code example produces output similar to the following:
//
//Method: Void MethodBodyExample(System.Object)
// Local variables are initialized: True
// Maximum number of items on the operand stack: 2
End Sub
' This test method is executed at the beginning of Main, to show
' how the Filter clause works. The Filter clause is generated by
' a Visual Basic When expression. If arg is Nothing, this method
' throws ArgumentNullException, which is caught by the filter
' clause. If arg is a string, the method throws ArgumentException,
' which does not match the filter clause.
'
' Sub Main also contains code to analyze this method, using
' the properties and methods of the MethodBody class.
Public Sub MethodBodyExample(ByVal arg As Object)
' Define some local variables. In addition to these variables,
' the local variable list includes the variables scoped to
' the catch clauses.
Dim var1 As Integer = 42
Dim var2 As String = "Forty-two"
Try
' Depending on the input value, throw an ArgumentException or
' an ArgumentNullException to test the Catch clauses.
'
If arg Is Nothing Then
Throw New ArgumentNullException("The argument cannot be Nothing.")
End If
If arg.GetType() Is GetType(String) Then
Throw New ArgumentException("The argument cannot be a string.")
End If
' The When expression makes this a filter clause. The expression
' selects only exceptions that derive from the ArgumentException
' class. Other exceptions, including ArgumentException itself,
' are not handled by this filter clause.
Catch ex As ArgumentException _
When ex.GetType().IsSubclassOf(GetType(ArgumentException))
Console.WriteLine("Filter clause caught: {0}", ex.GetType())
' This catch clause handles the ArgumentException class, and
' any other class derived from Exception.
Catch ex As Exception
Console.WriteLine("Ordinary exception-handling clause caught: {0}", _
ex.GetType())
Finally
var1 = 3033
var2 = "Another string."
End Try
End Sub
End Class
' This code example produces output similar to the following:
'
'Ordinary exception-handling clause caught: System.ArgumentException
'Filter clause caught: System.ArgumentNullException
'
'Method: Void MethodBodyExample(System.Object)
' Local variables are initialized: True
' Maximum number of items on the operand stack: 3
//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
//
//Filter
// Filter Offset: 71
// Handler Length: 23
// Handler Offset: 116
// Try Block Length: 61
// Try Block Offset: 10
//Clause
// Type of exception: System.Exception
// Handler Length: 21
// Handler Offset: 70
// Try Block Length: 61
// Try Block Offset: 9
//Finally
// Handler Length: 14
// Handler Offset: 94
// Try Block Length: 85
// Try Block Offset: 9
'
'Filter
' Filter Offset: 0
' Handler Length: 19
' Handler Offset: 99
' Try Block Length: 45
' Try Block Offset: 9
'Clause
' Type of exception: System.Exception
' Handler Length: 25
' Handler Offset: 118
' Try Block Length: 45
' Try Block Offset: 9
'Finally
' Handler Length: 13
' Handler Offset: 153
' Try Block Length: 144
' Try Block Offset: 9
Comentários
Observação
Trabalhar com cláusulas de tratamento de exceções requer uma compreensão completa dos metadados e dos formatos de instrução msil (microsoft intermediate language). As informações podem ser encontradas na documentação da CLI (Common Language Infrastructure), especialmente "Partição II: Definição e Semântica de Metadados".