Open a file. The mode can be 'r' (default), 'w', 'x' or 'a' for reading, writing, exclusive creation or appending. The file will be created if it doesn't exist when opened for writing or appending; it will be truncated when opened for writing. A FileExistsError will be rai
(self, file, mode='r', closefd=True, opener=None)
| 1485 | _closefd = True |
| 1486 | |
| 1487 | def __init__(self, file, mode='r', closefd=True, opener=None): |
| 1488 | """Open a file. The mode can be 'r' (default), 'w', 'x' or 'a' for reading, |
| 1489 | writing, exclusive creation or appending. The file will be created if it |
| 1490 | doesn't exist when opened for writing or appending; it will be truncated |
| 1491 | when opened for writing. A FileExistsError will be raised if it already |
| 1492 | exists when opened for creating. Opening a file for creating implies |
| 1493 | writing so this mode behaves in a similar way to 'w'. Add a '+' to the mode |
| 1494 | to allow simultaneous reading and writing. A custom opener can be used by |
| 1495 | passing a callable as *opener*. The underlying file descriptor for the file |
| 1496 | object is then obtained by calling opener with (*name*, *flags*). |
| 1497 | *opener* must return an open file descriptor (passing os.open as *opener* |
| 1498 | results in functionality similar to passing None). |
| 1499 | """ |
| 1500 | if self._fd >= 0: |
| 1501 | # Have to close the existing file first. |
| 1502 | self._stat_atopen = None |
| 1503 | try: |
| 1504 | if self._closefd: |
| 1505 | os.close(self._fd) |
| 1506 | finally: |
| 1507 | self._fd = -1 |
| 1508 | |
| 1509 | if isinstance(file, float): |
| 1510 | raise TypeError('integer argument expected, got float') |
| 1511 | if isinstance(file, int): |
| 1512 | if isinstance(file, bool): |
| 1513 | import warnings |
| 1514 | warnings.warn("bool is used as a file descriptor", |
| 1515 | RuntimeWarning, stacklevel=2) |
| 1516 | file = int(file) |
| 1517 | fd = file |
| 1518 | if fd < 0: |
| 1519 | raise ValueError('negative file descriptor') |
| 1520 | else: |
| 1521 | fd = -1 |
| 1522 | |
| 1523 | if not isinstance(mode, str): |
| 1524 | raise TypeError('invalid mode: %s' % (mode,)) |
| 1525 | if not set(mode) <= set('xrwab+'): |
| 1526 | raise ValueError('invalid mode: %s' % (mode,)) |
| 1527 | if sum(c in 'rwax' for c in mode) != 1 or mode.count('+') > 1: |
| 1528 | raise ValueError('Must have exactly one of create/read/write/append ' |
| 1529 | 'mode and at most one plus') |
| 1530 | |
| 1531 | if 'x' in mode: |
| 1532 | self._created = True |
| 1533 | self._writable = True |
| 1534 | flags = os.O_EXCL | os.O_CREAT |
| 1535 | elif 'r' in mode: |
| 1536 | self._readable = True |
| 1537 | flags = 0 |
| 1538 | elif 'w' in mode: |
| 1539 | self._writable = True |
| 1540 | flags = os.O_CREAT | os.O_TRUNC |
| 1541 | elif 'a' in mode: |
| 1542 | self._writable = True |
| 1543 | self._appending = True |
| 1544 | flags = os.O_APPEND | os.O_CREAT |