# draft of file-backed list # like everything, it needs to be refactored to use list and database abstractions import os class FileBackedList: def __init__(self, filename): try: self.file = open(filename, 'x+t') except FileExistsError: self.file = open(filename, 'r+t') self.offsets = [] while True: self.offsets.append(self.file.tell()) if self.file.readline() == '': break def __getitem__(self, offset): self.file.seek(self.offsets[offset]) return self.file.readline()[:-1] def append(self, line): self.file.seek(0, os.SEEK_END) endpos = self.file.tell() self.file.write(line + '\n') self.offsets.append(endpos) def __iadd__(self, other): assert type(other) is str return self.append(other) def __del__(self): self.file.close() # maybe it is not ok. it is a draft and has many errors.