' This code is taken from Francesco Balena's' "Programming Microsoft Visual Basic .NET" - MS Press 2002, ISBN 0735613753' You can read a free chapter of the book at ' http://www.vb2themax.com/HtmlDoc.asp?Table=Books&ID=101000Imports System.ReflectionModule MainModule Sub Main() ' Get command-line arguments. Dim args() As String = Environment.GetCommandLineArgs() Dim cmd As String = Environment.CommandLine Dim ty As Type Dim mbrTypes As MemberTypes = MemberTypes.All Dim mbrName As String = "" Dim mi As MemberInfo ' If no arguments, /? or /help If args.Length <= 1 OrElse args(1) = "/?" OrElse String.Compare(args(1), _ "/help", True) = 0 Then ' Show command-line syntax and exit. Console.WriteLine("Command-line Type Browser - by Francesco Balena") Console.WriteLine(" Syntax: typebrow typename [membername[*]]") Exit Sub End If Dim i As Integer = args(1).IndexOf(","c) If i < 0 Then ' Create the type as specified by first argument. ty = Type.GetType(args(1), False, True) Else ' Create the assembly specified in the last part of the first ' argument Dim asmname As String = args(1).Substring(i + 1) Dim asm As [Assembly] = [Assembly].LoadWithPartialName(asmname) ' Get the type in the specified assembly. ty = asm.GetType(args(1).Substring(0, i), False, True) End If If ty Is Nothing Then ' Exit if error. Console.WriteLine("Unable to create type ""{0}""", args(1)) Exit Sub End If ' If the user asked for a particular name. If args.Length > 2 Then ' Retrieve the name mbrName = args(2) End If ' Get the list of member info to be displayed Dim minfos() As MemberInfo = ty.FindMembers(mbrTypes, _ BindingFlags.Public Or BindingFlags.Instance Or BindingFlags.Static, _ AddressOf CustomMemberFilter, mbrName) ' Display information on all these members. For Each mi In minfos Console.WriteLine(MemberDescription(mi)) Next End Sub ' This is the custom filter for members. ' On entry filterCriteria holds the name of the member we're looking for. ' (Supports partial names with a trailing asterisk, as in "Repl*".) Function CustomMemberFilter(ByVal m As MemberInfo, _ ByVal filterCriteria As Object) As Boolean ' Discard accessor methods for properties. If m.Name.StartsWith("get_") Or m.Name.StartsWith("set_") Then Return False End If ' Get the search filter in uppercase. Dim search As String = filterCriteria.ToString.ToUpper If search = "" Then Return True If search.EndsWith("*") Then ' If there is a trailing asterisk, checks for partial match. If m.Name.ToUpper.StartsWith(search.Substring(0, _ search.Length - 1)) Then Return True Else ' Otherwise search for exact match. If m.Name.ToUpper = search Then Return True End If End Function ' Return the syntax for a member (field, property, methods, event). Function MemberDescription(ByVal mi As MemberInfo) As String Dim res As String ' Different treatment for different types Select Case mi.MemberType Case MemberTypes.Field ' Fields: append As clause. Dim fdi As FieldInfo = CType(mi, FieldInfo) res &= NameDescription(mi, fdi.IsStatic) & VBTypeDescription _ (fdi.FieldType) Case MemberTypes.Property ' Properties: append parameter list and return type. Dim pri As PropertyInfo = CType(mi, PropertyInfo) res &= NameDescription(mi, False) & ParamListDescription _ (pri.GetIndexParameters) res &= VBTypeDescription(pri.PropertyType) Case MemberTypes.Method ' Methods: append parameter list and return type. Dim mti As MethodInfo = CType(mi, MethodInfo) res &= NameDescription(mi, mti.IsStatic) & ParamListDescription _ (mti.GetParameters) If Not (mti.ReturnType Is Nothing) Then res &= VBTypeDescription(mti.ReturnType, True) End If Case MemberTypes.Constructor ' Constructor Dim cti As ConstructorInfo = CType(mi, ConstructorInfo) res &= NameDescription(mi, False) & ParamListDescription _ (cti.GetParameters) Case MemberTypes.Event ' Events: append parameter list. Dim evi As EventInfo = CType(mi, EventInfo) ' Get the type that corresponds to the underlying delegate. Dim delType As Type = evi.EventHandlerType Dim mi2 As MethodInfo = delType.GetMethod("Invoke") res &= NameDescription(mi, False) & ParamListDescription _ (mi2.GetParameters) End Select Return res End Function ' Return a description for name. ' (Including Shared and member type description.) Function NameDescription(ByVal mi As MemberInfo, ByVal IsStatic As Boolean) _ As String Dim res As String ' Prefix with Shared if necessary If IsStatic Then res = "Shared " End If ' Append member type, but distinguish between Sub and Function If mi.MemberType <> MemberTypes.Method Then ' if not a method, we can simply use the Enum.Format method. res &= [Enum].Format(mi.MemberType.GetType, mi.MemberType, _ "G") & " " Else Dim meth As MethodInfo = CType(mi, MethodInfo) If meth.ReturnType.Name = "Void" Then res &= "Sub " Else res &= "Function " End If End If ' Append name and return to caller. If mi.MemberType = MemberTypes.Constructor Then ' Visual Basic constructors are named "new" res &= "New" Else ' A non-constructor element. res &= mi.Name End If Return res End Function ' Return the description for a list of parameters. Function ParamListDescription(ByVal pinfos() As ParameterInfo) As String Dim res As String = "(" Dim i As Integer ' Iterate over all parameters. For i = 0 To pinfos.GetUpperBound(0) ' Append description for this parameter. res &= ParamDescription(pinfos(i)) ' Append a comma if this isn't the last argument. If i < pinfos.GetUpperBound(0) Then res &= ", " Next ' Close the parenthesis and return to caller. Return res & ")" End Function ' Return a description for a single parameter. Function ParamDescription(ByVal pi As ParameterInfo) As String Dim res As String Dim pt As Type = pi.ParameterType ' Start with Optional if necessary. If pi.IsOptional Then res = "Optional " ' Append ByVal or ByRef. If pt.IsByRef Then res &= "ByRef " Else res &= "ByVal " End If ' Append the parameter name. res &= pi.Name ' Append the type, but convert it to VB syntax. res &= VBTypeDescription(pt) ' Append the default value, if there is one. If pi.IsOptional Then ' Enclose the default value within quotes if it is a string. If pt Is GetType(System.String) Then res &= " = """ & pi.DefaultValue.ToString & """" Else res &= " = " & pi.DefaultValue.ToString End If End If ' Return to the caller. Return res End Function ' Return a parameter type in VB-friendly format. Function VBTypeDescription(ByVal ty As Type, _ Optional ByVal PostfixArrayMarks As Boolean = False) As String Dim res As String ' Get the return type as a string. res &= ty.Name ' Drop trailing "[]" pair, is there is one. If res.EndsWith("[]") Then res = res.Substring(0, res.Length - 2) End If ' Drop trailing *, if there is one. If res.EndsWith("*") Then res = res.Substring(0, res.Length - 1) End If ' Adjust for VB-friendly names. Select Case res Case "Int16" res = "Short" Case "Int32" res = "Integer" Case "Int64" res = "Long" Case "Void" ' this is the type "returned" by Sub Return "" End Select ' Append "AS" and "()" if this is an array. If Not ty.IsArray Then res = " As " & res ElseIf PostfixArrayMarks Then ' Append trailing () pair. res = " As " & res & "()" Else ' Prefix leading () pair. res = "() As " & res End If ' Return to the caller. Return res End FunctionEnd Module


What is Metadata?
What is metadata? Well, It’s an odd concept to wrap your head around. Metadata is essentially the secondary layer of data that tracks details about the “regular” data. The regular