[Python-3000] TextIOWrapper.write(s:str) and bytes in py3k-struni (original) (raw)

Christian Heimes lists at cheimes.de
Sat Jul 14 15:36:04 CEST 2007

Hello!

I'm having some troubles with unit tests in the py3k-struni branch. Some test like test_uu are failing because an io.TextIOWrapper instance's write() method doesn't handle bytes. The method is defined as:

def write(self, s: str):
    if self.closed:
        raise ValueError("write to closed file")
    # XXX What if we were just reading?
    b = s.encode(self._encoding)
    if isinstance(b, str):
        b = bytes(b)
    n = self.buffer.write(b)
    if "\n" in s:
        # XXX only if isatty
        self.flush()
    self._snapshot = self._decoder = None
    return len(s)

The problematic lines are the lines from s.encode() to b = bytes(b). The behavior is more than questionable. A bytes object doesn't have an encode() method and str's encode method() always returns bytes. IMO the write() method should be changed to:

def write(self, s: (str, bytes)):
    if self.closed:
        raise ValueError("write to closed file")
    # XXX What if we were just reading?
    if isinstance(s, basestring):
        b = s.encode(self._encoding)
    elif isinstance(s, bytes):
        b = s
    else:
        b = bytes(b)
    n = self.buffer.write(b)
    if b"\n" in b:
        # XXX only if isatty
        self.flush()
    self._snapshot = self._decoder = None
    return len(s)

Or the write() should explictly raise a TypeError when it is not allowed to handle bytes.

Christian

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