Using GetAssemblyInfo to locate and instantiate a variable, using Reflection

Introduction

How to use reflection to find out all the types in an assembly.

First off, get the assembly from type integer. This should get the mscorlib.dll. (Main .NET assembly).

SampleAssembly = [Assembly].GetAssembly(Integer1.GetType())

Now, get the types from it:

types = SampleAssembly.GetTypes()

Now, get an object from the types array.

obj = types(i).InvokeMember(Nothing, _
    BindingFlags.DeclaredOnly Or BindingFlags.Public_
    Or BindingFlags.NonPublic Or BindingFlags.Instance_
    Or BindingFlags.CreateInstance, Nothing,_
    types(i), Nothing)

To get all of the Fields (Public variables), call GetFields. (However, you could call GetProperties or GetMethods which work very similar.)

fields = obj.GetType().GetFields((BindingFlags.Public Or BindingFlags.Static))

To get a value from a field, use .GetValue from the field. (You may not want to cast to string.) (CType is VB's ugly way of casting)

strResult = CType(fields(i2).GetValue(Nothing), String)

The Code

Option Explicit On 
Imports System
Imports System.Reflection
Imports System.Text.RegularExpressions
Imports Microsoft.VisualBasic

Public Class GetAssemblyInfo

    Public Class RequiredInfo
        Public strDataType As String
        Public strSize As String
        Public strMin As String
        Public strMax As String
    End Class
    Public Function getInfo(ByVal strType As String) As RequiredInfo
        Dim SampleAssembly As [Assembly]
        Dim Integer1 As New Int32
        Dim typeInt As Type
        Dim types() As Type
        Dim obj As [Object]
        Dim fields As FieldInfo()
        Dim intfieldValue As Integer
        Dim fltfieldValue As Single
        Dim strResult As String

        Dim rqInfo As New RequiredInfo
        ' Set the Type instance to the target class type.
        typeInt = Integer1.GetType()
        ' Instantiate an Assembly class to the assembly housing the Integer type.  
        SampleAssembly = [Assembly].GetAssembly(Integer1.GetType())
        ' Gets the location of the assembly using file: protocol.
        'Console.WriteLine(("CodeBase=" + SampleAssembly.CodeBase))

        types = SampleAssembly.GetTypes()
        Dim strTypeDesc As String
        For i As Integer = 0 To types.Length - 1
            If (types(i).Name() = strType) Then
                rqInfo.strDataType = types(i).Name()
               obj = types(i).InvokeMember(Nothing, _
                     BindingFlags.DeclaredOnly _
                     Or BindingFlags.Public _
                     Or BindingFlags.NonPublic Or _
                     BindingFlags.Instance Or _
                     BindingFlags.CreateInstance, _
                     Nothing, types(i), Nothing)
                fields = obj.GetType().GetFields((BindingFlags.Public_
                     Or BindingFlags.Static))
                For i2 As Integer = 0 To fields.Length - 1
                    If (fields(i2).Name = "MaxValue") Then
                        strResult = CType(fields(i2).GetValue(Nothing), String)
                        rqInfo.strMax = strResult

                    End If
                    If (fields(i2).Name = "MinValue") Then
                        strResult = CType(fields(i2).GetValue(Nothing), String)
                        rqInfo.strMin = strResult
                    End If
                Next i2
                rqInfo.strSize = Len(obj)
                Return rqInfo
            End If
        Next
    End Function

End Class 'AssemblyName_GetAssemblyName

Here is the Module

'/////////////////////////////////////////////////////////////////////////////
Option Explicit On

Module modCallAssemblyInfo

    Sub Main()
        Dim getAssInfo As New GetAssemblyInfo

        Dim reqInfo As GetAssemblyInfo.RequiredInfo = getAssInfo.getInfo("Single")
        Dim InitReqInfo As New GetAssemblyInfo.RequiredInfo

        InitReqInfo.strDataType = "Data Type"
        InitReqInfo.strMax = "MaxValue"
        InitReqInfo.strMin = "MinValue"
        InitReqInfo.strSize = "Size (Bytes)"

        Console.WriteLine("___________________________" &_ 
            "____________________________________________") '40
        Write(InitReqInfo)
        Write(getAssInfo.getInfo("Int16"))
        Write(getAssInfo.getInfo("Int32"))
        Write(getAssInfo.getInfo("Int64"))
        Write(getAssInfo.getInfo("Single"))
        Write(getAssInfo.getInfo("Double"))
    End Sub

    Public Sub Write(ByRef info As GetAssemblyInfo.RequiredInfo)
        Console.WriteLine("{0,-15}|{1,-15}|{2,-25}|{3,-20}",_
         info.strDataType, info.strSize,_
         info.strMin, info.strMax)
    End Sub

End Module

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