public MultiFile(IFileSystem fileSystem, FileSystemPath directoryPath, string prefix)
: base(fileSystem)
{
ArgAssert.NotNull(directoryPath, "directoryPath");
ArgAssert.NotNull(prefix, "prefix");
ArgAssert.That(prefix != "", "prefix", "not be empty");
FileSystem.AssertDirectory(directoryPath);
_directoryPath = directoryPath;
_prefix = prefix;
_files = new List <MultiFileFile>();
Populate();
}