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MethodBase.GetMethodBody Method

When overridden in a derived class, gets a MethodBody object that provides access to the MSIL stream, local variables, and exceptions for the current method.

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

'Declaration
<ReflectionPermissionAttribute(SecurityAction.Demand, Flags := ReflectionPermissionFlag.MemberAccess)> _
Public Overridable Function GetMethodBody As MethodBody

Return Value

Type: System.Reflection.MethodBody
A MethodBody object that provides access to the MSIL stream, local variables, and exceptions for the current method.

ExceptionCondition
InvalidOperationException

This method is invalid unless overridden in a derived class.

You do not have to override the GetMethodBody in order to use it. You can call the GetMethodBody method on MethodInfo and ConstructorInfo objects, because the method is overridden in the runtime versions of these classes. For example, the runtime version of the MethodInfo class derives from the MethodInfo class, which in turn derives from the MethodBase class.

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 LocalVariables property is used to obtain a list of LocalVariableInfo objects and display their types and index order. The ExceptionHandlingClauses property is used to obtain a list of exception-handling clauses.

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.

Imports System
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

.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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