Question

I’m struggling with a small issue with regard to how I go about refactoring this to a decent pattern.

public class DocumentLibrary
{
    private IFileSystem fileSystem;
    private IDocumentLibraryUser user;

    public DocumentLibrary(IDocumentLibraryUser user) : this(user, FileSystemFrom(user)) { }

    public DocumentLibrary(IDocumentLibraryUser user, IFileSystem fileSystem)
    {
        this.user = user;
        this.fileSystem = fileSystem;
    }

    public void Create(IWorkerDocument document)
    {
        document.SaveTo(fileSystem);
    }

    public IWorkerDocument AttemptContractRetrieval()
    {
        return new Contract(fileSystem, user);
    }

    public IWorkerDocument AttemptAssignmentRetrieval()
    {
        return new Assignment(fileSystem, user);
    }

    private static IFileSystem FileSystemFrom(IDocumentLibraryUser user)
    {
        var userLibraryDirectory = new DirectoryInfo("/DocLib/" + EnvironmentName() + "/" + user.Id);
        return new FileSystem(userLibraryDirectory);
    }

    private static string EnvironmentName()
    {
        using (var edmxContext = new Entities())
        {
            return (from setting in edmxContext.EnvironmentSettings
                         where setting.Name == "EnvironmentName"
                         select setting.Value).First(); 
        }
    }
}

I have two types of worker documents, but I can’t seem to easily refactor the two methods above (AttemptContractRetrieval and AttemptAssignmentRetrieval) to a decent form.

Any help would be much appreciated.

Regards,
Jim.

Answer 1

Personnally, I would consider either a factory pattern using factory methods or a builder pattern.

Good use of the factory pattern can be seen in the Enterprise Library solution e.g:
Database.CreateDatabase();
I would say this would be the most straight forward to integrate.

If you chose the Builder pattern, with a requirement to create more complex objects, then you can separate out the creation of complex objects into a series of build commands e.g:
vehicleBuilder.BuildFrame();
vehicleBuilder.BuildEngine();
vehicleBuilder.BuildWheels();
vehicleBuilder.BuildDoors();

Then within these methods, given your chosen implementation, you can add your complexity but make the method calls and construction quite straight forward.

If you haven’t come across it, http://www.dofactory.com is a good place to go.