The article demonstrates how BASIC-like languages can be extended using the object oriented programming (OOP) concept of encapsulation to protect private variables. The article covers benefits and provides examples of how these modern concepts can further benefit non-OOP languages.

First part
http://www.intl-spectrum.com/mag/MARAPR.2010/default.aspx

Second part
http://www.intl-spectrum.com/mag/JANFEB.2010/default.aspx

The entire magazine is available for PDF download. No registration required.

The Visual Basic .NET example code below loads SampleAppV1\DotNetLibrary.DLL and AnotherSampleAppV2\DotNetLibrary.DLL which are different versions of the same assembly.

'Load assembly using reflection from the file specified so we can get information about it
Dim DLLAssemblyInfo As System.Reflection.Assembly
DLLAssemblyInfo = System.Reflection.Assembly.LoadFrom("\\\\appserver.company.int\\SampleAppV1\\DotNetLibrary.DLL")

'Now load the assembly from the GAC using the information in the file. 
Dim GACDLL As System.Reflection.Assembly
GACDLL = System.Reflection.Assembly.Load(AssemblyInfo.FullName, DLLAssemblyInfo.Evidence)

'Load the second version of the same assembly from the newer application
Dim DLLAssemblyInfoV2 As System.Reflection.Assembly
DLLAssemblyInfoV2 = System.Reflection.Assembly.LoadFrom("\\\\appserver.company.int\\AnotherSampleAppV2\\DotNetLibrary.DLL")

'Again, use the DLL information from the assembly file to load the assembly from the GAC
Dim GACDLLv2 As System.Reflection.Assembly
GACDLLv2 = System.Reflection.Assembly.Load(AssemblyInfoV2.FullName, DLLAssemblyInfoV2.Evidence)

'At this point in the code we have references to both assemblies loaded from the GAC. The next step is to instantiate an object from each of the references.

'Get an MyAssembly.Library from the old version and run the version method
Dim GACDLLType As Type = GACDLL.GetType("MyAssembly.Library")
Dim MyLibV1 As Object = Activator.CreateInstance(GACDLLType)
Dim v1 As String
v1 = MyLibV1.Version

'Finally, do the same and get the new MyAssembly.Library
Dim GACDLLTypeV2 As Type = GACDLLV2.GetType("MyAssembly.Library")
Dim MyLibV2 As Object = Activator.CreateInstance(GACDLLTypeV2)
Dim v2 As String
v2 = MyLibV2.Version

The variables v1 and v2 were both retrieved from the MyAssembly.Library.Version() method but the variables will not contain the same value because different versions of the assembly were loaded from the GAC during the System.Reflection.Assembly.Load() call.

Why not just load the assembly from each of the DLL files instead of the GAC? Security restrictions prevented untrusted assemblies from being loaded over the network. A possible work around would be to trust the network location or sign the assemblies and trust the signer but that remains for another posting.

When the script below is executed it checks to see if it was passed a command line argument named "elevated". If it is not found the script recursively calls itself passing the elevated command line argument and requests to be run as administrator. The user is prompted to confirm the action and the restricted script exits leaving the escalated administrator script running. When the user grants permission the elevated argument is found and the script changes back from the %System32% working directory to the script where the script is located.

If WScript.Arguments.Named.Exists("elevated") = False Then

	'Launch the script again as administrator

	CreateObject("Shell.Application").ShellExecute "wscript.exe", """" & WScript.ScriptFullName & """ /elevated", "", "runas", 1

	WScript.Quit

Else

	'Change the working directory from the system32 folder back to the script's folder.

	Set oShell = CreateObject("WScript.Shell")

	oShell.CurrentDirectory = CreateObject("Scripting.FileSystemObject").GetParentFolderName(WScript.ScriptFullName)

	MsgBox "Now running with elevated permissions"

End If

Normally, people input questions and keywords into Google to find an answer. In my case the answer was known. Use caspol.exe with the -pub -file arguments to trust all the assemblies signed with my certificate. The MSDN caspol.exe documentation was helpful but the exact syntax for implementing the command was a little fuzzy.

When in doubt Google it. Behold, the question to my answer stated in a question:

"What does this statement do? caspol -machine -addgroup All_Code -pub -file MyApp.exe FullTrust"

Thanks to Matthew Podwysocki his question fit my answer and provided the syntax needed to complete my work with caspol.

1. Comment, comment, comment. If you make a change to a PHP file or template that was supplied by the vendor make a comment. Know what line the change started and where the change ends. When manually patching the file the comments will keep you from having to guess if a change is a patch from the vendor or a customization you made.
2. When making a customization, comment out the original code block using block comments (not line comments) and make your changes to a copy of the original code block. Eventually when the original code gets patched or updated by the vendor you will still have a reference to the original code and a utility like WinMerge will be able to help match up the changes to the original code.
3. For files that need manual patching use a utility such as WinMerge to find and resolve conflicts. If you make ample comments and left original code blocks in place WinMerge will better be able to help you get the file patches and your customizations back in place.

Good luck on patching your custom cart!