Design Patterns... [Resolved]

[<ABX]

Lets say I have a Class Named DataChunk each data chunk class has a header, this header has some basic Information on what the DataChunk contains.

Based on the name that Header Contains I need to figure out what Parsing class should be created and then add it to a collection

This is a basic version of the class

Interface IParseable
 
Sub Read(byref Reader as BinaryReader)
Sub Write(byRef Writer as BinaryWriter)
 
End Interface

Public Class DataChunk
    Implements IParsable
 
    Public Sub New(byRef Reader as BinaryReader)
         Read(Reader)
    End Sub
 
    Private _Header as ChunkHeader
 
    Public Sub Read(byRef Reader as BinaryReader)
        _Header = New ChunkHeader(Reader)
       '
    End Sub
 
    'Write sub here (but not really relevant)
 
End Class

ChunkHeader also Implements IParseable.

basicly There are many different types of dataChunk's, the Header's name property is what should be used to decide what class should be used to continue parsing.

These data chunks need to be stored in a typed collection so I was thinking of Inheriting Declaring dataChunk as MustOverride...

eg..

Public Class DataChunk
    Implements IParsable
 
    Public Sub New(byRef Reader as BinaryReader)
         Read(Reader)
    End Sub
 
    Private _Header as ChunkHeader
 
    Public Sub Read(byRef Reader as BinaryReader)
        _Header = New ChunkHeader(Reader)
        ParseData(Reader)
    End Sub
 
    Public Sub Write(byRef Writer as BinaryWriter)
       _Header.Write(Writer)
       RenderData(Writer)
    End Sub
 
    Public MustOverride Sub ParseData(byRef Reader as BinaryReader)
    Public MustOverride Sub RenderData(byRef Writer as BinaryWriter)
    Public MustOverride Function CanParse(DataChunkName as String)
 
End Class

but then how do I dynamicly create an instance of the proper class only knowing the DataChunkName

[<ABX]

I'm still completely clueless...

[<ABX]

Well I came up with a partial solution:

I created another interface for (IDataChunk)
ParseData, RenderData, CanParse.

Now how should I enumerate the parsing classes?

I could use reflection to get a array of all the types that Implement IDataChunk, but speed is an issue in the project.

I could hard code the List of parsing classes into the application, but It just seems.... un-elegant. (if this is the BEST method for speed/maintenance, I will do it this way).

Any other suggestions?

Edit: Never Mind... I jumped the gun.

[Briantcva]

In pattern speak, sounds "Factory"-ish. I know the idea of a [possibly] long select case sounds inelegant, but it's often the way to go - and more of an abstraction than it might seem at first blush. Look here - might get you on your way (seem like you probably want the simple factory - not [necessarily] the abstract one).

[<ABX]

I think I will need the abstract factory (the version I posted here was simplifed). Don't have time to implement it now, but thanks.