def disposition_init(cls, original_filename):
    """Construct and initialize a new FileDisposition object."""
    disp = cls()
    disp.original_filename = original_filename
    disp.canonical_filename = original_filename
    disp.source_filename = None
    disp.trace = False
    disp.reason = ""
    disp.file_tracer = None
    disp.has_dynamic_filename = False
    return disp