Decouple Writable, Directory and File interfaces from disk IO about cwa-server HOT 1 CLOSED

interface Writable {
    /*...*/
}

abstract class AbstractWritable implements Writable {
    /*... Writable functionality ...*/
}

abstract class WritableOnDisk extends AbstractWritable {
    /*... Disk IO functionality for Writable ...*/
}

interface File extends Writable {
    /*...*/
}

abstract class AbstractFile extends AbstractWritable implements File {
    /*... File functionality ...*/
}

abstract class FileOnDisk extends AbstractFile, WritableOnDisk implements File {
    //                            ^^^^^^^^^^^^^^^^^^^^^^^^^^^^
    //                                     No can do ...
    /*... Disk IO functionality for File ...*/
}