Why can't I declare a property as System.IO.Path - vb.net

Question

I am using a custom class to pass data between methods. One of the primary functions is image handling so I have an image path and a custom thumb path as properties of my class. I want to use the methods included with the System.IO.Path class as part of the properties, but I can't seem to do it this way.
I know how to get this to work by using a string type instead of System.IO.Path as a type so I don't need anyone to tell me how to do it that way. I just think that being able to declare my ImagePath as System.IO.Path would be so much easier because I can use the Path methods on my ImagePath property. I must be missing some understanding about declaring types and I'm hoping I can learn from this question.
How the class is defined:
Public Class myClass
'structured information which will be passed to a replicator
Public Property ID As Integer
Public Property ImagePath As System.IO.Path '<== this doesn't work
Public Property ThumbPath As System.IO.Path '<== this doesn't work
Public Property GroupID As Byte
Public Property SystemID As Byte
Public Property Comment As String
'Other properties
End Class
How I would like to use this class:
Public Function myReplicatorFunc(myObj as myClass)
Dim myTempPath as string
Dim myDBObj as myDBConnection
'handle database connections
myTempPath = myObj.ImagePath.GetDirectoryName() & "\" _
myDBObj.GetIntID.toString() & "\" _
myObj.ImagePath.GetExtension()
My.Computer.FileSystem.RenameFile(myObj.ThumbPath.toString, myTempPath)
'Other file movements for replication etc
End Function
Why can't I declare a property as a System.IO.Path class? If the answer is just "NO" for some reason (please explain why) then how can I use the System.IO.Path methods as extensions to my properties without re-writing as a custom class with exact copies of the same methods?

Answer 1

You cannot declare an instance of System.IO.Path because it's a static class - it cannot be instantiated. Think of it as simply a grouping of path-related global functions under a System.IO.Path namespace. (The real namespace is just System.IO but because Path is a static class, functionally it really behaves as if was just a namespace for a bunch of related global functions.)
Your ImagePath property needs to be string and you just need to pass it to Path functions when you need that logic. This is somewhat unfortunate.
As an alternative, you can create a new class (sorry, C# code; I'm not a VB.NET expert):
using System;
using System.IO;
// import namespaces as necessary
public class Filename
{
private string m_sFilename;
public Filename ( string sFilename )
{
m_sFilename = sFilename;
}
public string FullName
{
get
{
return ( m_sFilename );
}
set
{
m_sFilename = value;
}
}
public string FolderName
{
get
{
return ( Path.GetDirectoryName ( m_sFilename ) );
}
}
// Add more properties / methods
...
}
Once you have this class, you can write:
private Filename m_oImagePath = null;
I did pretty much the same in my project because having a specific type for folder / file paths makes it easier to update logic related to operations on path names.

Answer 2

Why not use DirectoryInfo like:
Public Property ImagePath As System.IO.DirectoryInfo
Public Property ThumbPath As System.IO.DirectoryInfo