MethodBody Classe
Definizione
Importante
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Fornisce l'accesso ai metadati e al linguaggio MSIL (Microsoft Intermediate Language) relativi al corpo di un metodo.
public ref class MethodBodypublic ref class MethodBody sealedpublic class MethodBody[System.Runtime.InteropServices.ComVisible(true)]
public sealed class MethodBody[System.Runtime.InteropServices.ComVisible(true)]
public class MethodBodytype MethodBody = class[<System.Runtime.InteropServices.ComVisible(true)>]
type MethodBody = classPublic Class MethodBodyPublic NotInheritable Class MethodBody- Ereditarietà
-
MethodBody
- Attributi
Esempio
Nell'esempio di codice seguente viene definito un metodo di test denominato MethodBodyExample e vengono visualizzate le informazioni sulle variabili locali e le clausole di gestione delle eccezioni. Il MethodBase.GetMethodBody metodo viene utilizzato per ottenere un MethodBody oggetto per il metodo di test.
Nell'esempio viene utilizzata la LocalVariables proprietà per ottenere un elenco di oggetti e quindi vengono visualizzati i tipi e l'ordine di LocalVariableInfo indice. La ExceptionHandlingClauses proprietà viene utilizzata per ottenere un elenco di clausole di gestione delle eccezioni.
#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 information about the local variables in the
// method body.
Console::WriteLine();
for each (LocalVariableInfo^ lvi in mb->LocalVariables)
{
Console::WriteLine("Local variable: {0}", lvi);
}
// 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);
}
}
//This code example produces output similar to the following:
//
//Method: Void MethodBodyExample(System.Object)
// Local variables are initialized: False
// Maximum number of items on the operand stack: 4
//
//Local variable: System.ArgumentException (0)
//Local variable: System.String (1)
//Local variable: System.Int32 (2)
//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
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);
// Display information about the local variables in the
// method body.
Console.WriteLine();
foreach (LocalVariableInfo lvi in mb.LocalVariables)
{
Console.WriteLine("Local variable: {0}", lvi);
}
// 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);
}
}
// 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
//
//Local variable: System.Int32 (0)
//Local variable: System.String (1)
//Local variable: System.Exception (2)
//Local variable: System.Boolean (3)
//
//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
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 information about the local variables in the
' method body.
Console.WriteLine()
For Each lvi As LocalVariableInfo In mb.LocalVariables
Console.WriteLine("Local variable: {0}", lvi)
Next
' 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
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
'
'Local variable: System.Int32 (0)
'Local variable: System.String (1)
'Local variable: System.ArgumentException (2)
'Local variable: System.Exception (3)
'
'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
Commenti
La MethodBody classe fornisce l'accesso alle informazioni sulle variabili locali e sulle clausole di gestione delle eccezioni in un corpo del metodo e al linguaggio MSIL (Microsoft Intermediate Language) che costituisce il corpo del metodo.
È possibile usare i metodi di risoluzione del token della classe module, ad esempio ResolveType, ResolveMethode ResolveType, per risolvere i token nel corpo del metodo in Type oggetti, MethodInfo oggetti e FieldInfo oggetti che forniscono informazioni dettagliate sui tipi, i metodi e i campi a cui accede il codice MSIL nel corpo del metodo.
Nota
L'analisi dei corpi dei metodi richiede una conoscenza approfondita dei metadati e dei formati di istruzioni MSIL. Le informazioni sono disponibili nella documentazione di Common Language Infrastructure (CLI), in particolare "Partition II: Metadata Definition and Semantics".
Per ottenere un MethodBody oggetto per un determinato metodo, ottenere prima di tutto un MethodInfo oggetto per il metodo , quindi chiamare il MethodInfo metodo dell'oggetto GetMethodBody .
Costruttori
| MethodBody() |
Inizializza una nuova istanza della classe MethodBody. |
Proprietà
| ExceptionHandlingClauses |
Ottiene un elenco che include tutte le clausole di gestione delle eccezioni nel corpo del metodo. |
| InitLocals |
Ottiene un valore che indica se le variabili locali nel corpo del metodo sono inizializzate sui valori predefiniti dei tipi corrispondenti. |
| LocalSignatureMetadataToken |
Ottiene un token di metadati per la firma che descrive le variabili locali per il metodo nei metadati. |
| LocalVariables |
Ottiene l'elenco delle variabili locali dichiarate nel corpo del metodo. |
| MaxStackSize |
Ottiene il numero massimo di elementi nello stack di operandi durante l'esecuzione del metodo. |
Metodi
| Equals(Object) |
Determina se l'oggetto specificato è uguale all'oggetto corrente. (Ereditato da Object) |
| GetHashCode() |
Funge da funzione hash predefinita. (Ereditato da Object) |
| GetILAsByteArray() |
Restituisce il codice MSIL per il corpo del metodo come matrice di byte. |
| GetType() |
Ottiene l'oggetto Type dell'istanza corrente. (Ereditato da Object) |
| MemberwiseClone() |
Crea una copia superficiale dell'oggetto Object corrente. (Ereditato da Object) |
| ToString() |
Restituisce una stringa che rappresenta l'oggetto corrente. (Ereditato da Object) |