traceio.py

class TraceIO(object):
    def __init__(self, stream, log=print):
        self.stream = stream
        self.log = log

    def __enter__(self):
        return self.stream.__enter__()

    def __exit__(self, *args):
        return self.stream.__exit__(*args)

    def fileno(self):
        return self.stream.fileno()

    @property
    def closed(self):
        return self.stream.closed

    def close(self):
        self.log("close")
        self.stream.close()

    def flush(self):
        self.log("flush")
        self.stream.flush()

    def isatty(self):
        return self.stream.isatty()

    def readable(self):
        return self.stream.readable()

    def readline(self, size=-1):
        self.log("readline")
        return self.stream.readline(size)

    def readlines(self, hint=-1):
        self.log("readlines")
        return self.stream.readlines(hint)

    def seek(self, offset, whence=0):
        whence_term = {
            0: 'set',
            1: 'cur',
            2: 'end',
        }[whence]
        self.log("seek", offset, whence_term)
        return self.stream.seek(offset, whence)

    def seekable(self):
        return self.stream.seekable()

    def tell(self):
        return self.stream.tell()

    def truncate(self, size=None):
        self.log("truncate", repr(size))
        return self.stream.truncate(size)

    def writable(self):
        return self.stream.writable()

    def writelines(self, lines):
        for line in lines:
            self.write(line)

    def read(self, size=-1):
        if size == -1:
            return self.readall()
        self.log("read", size)
        return self.stream.read(size)

    def readall(self):
        self.log("readall")
        return self.stream.read(-1)

    def readinto(self, b):
        self.log("readinto", len(b))
        return self.stream.readinto(b)

    def write(self, b):
        self.log("write", len(b))
        return self.stream.write(b)

    def __iter__(self):
        while True:
            line = self.readline()

            if not line:
                break

            yield line