Python exception syntax error

Question

I'm implementing a fast copy function for Python (because ain't nobody got time for shutil) however I'm getting a syntax error E901 on this line except (IOError, os.error), why: Here's the full code:

class CTError(Exception):

    def __init__(self, errors):
        self.errors = errors
try:
    O_BINARY = os.O_BINARY
except:
    O_BINARY = 0
READ_FLAGS = os.O_RDONLY | O_BINARY
WRITE_FLAGS = os.O_WRONLY | os.O_CREAT | os.O_TRUNC | O_BINARY
BUFFER_SIZE = 128 * 1024


def copyfile(src, dst):
    try:
        fin = os.open(src, READ_FLAGS)
        stat = os.fstat(fin)
        fout = os.open(dst, WRITE_FLAGS, stat.st_mode)
        for x in iter(lambda: os.read(fin, BUFFER_SIZE), ""):
            os.write(fout, x)
    finally:
        try:
            os.close(fin)
        except:
            pass
        try:
            os.close(fout)
        except:
            pass


def copytree(src, dst, symlinks=False, ignore=[]):
    names = os.listdir(src)

    if not os.path.exists(dst):
        os.makedirs(dst)
    errors = []
    for name in names:
        if name in ignore:
            continue
        srcname = os.path.join(src, name)
        dstname = os.path.join(dst, name)
        try:
            if symlinks and os.path.islink(srcname):
                linkto = os.readlink(srcname)
                os.symlink(linkto, dstname)
            elif os.path.isdir(srcname):
                copytree(srcname, dstname, symlinks, ignore)
            else:
                copyfile(srcname, dstname)
            # XXX What about devices, sockets etc.?
        except (IOError, os.error), why: #XXX Here's the bug!
            errors.append((srcname, dstname, str(why)))
        except CTError, err:
            errors.extend(err.errors)
    if errors:
        raise CTError(errors)

Why is this syntax invalid?

As an aside, this looks like it basically works like the functions in shutil. See shutil.copyfileobj(). — Cyphase
– Cyphase, Commented Aug 18, 2015 at 22:52
There's some minor changes that, reading from the comments on the code,I wrote this a while ago, made it a little faster. Do you know any better method for fast directory and file transfer? — Bernardo Meurer
– Bernardo Meurer, Commented Aug 18, 2015 at 22:55

Thanatos · Accepted Answer · 2015-08-18 22:57:58Z

1

In Python 2, this fragment's syntax appears valid (CPython 2.7.10 accepts it on my machine).

In Python 3, this syntax isn't valid. The syntax,

except <TYPEEXPR>, <VAR>:

was deprecated. It was replaced with,

except <TYPEEXPR> as <VAR>:

in Python 3. E.g.,

except (IOError, os.error) as why:

This syntax is valid in Python 2 (it was added in 2.6, I believe), and I find it easier to read, so I'd recommend using it in Python 2 over the deprecated syntax as well, especially since it's forward-compatible and Python ≤2.5 usage is pretty small nowadays, and probably not worth supporting; I believe most libraries have dropped support.

answered Aug 18, 2015 at 22:57

Thanatos

44.7k17 gold badges99 silver badges152 bronze badges

Sign up to request clarification or add additional context in comments.

Collectives™ on Stack Overflow

Python exception syntax error

1 Answer 1

Comments

Your Answer

Hot Network Questions

Collectives™ on Stack Overflow

1 Answer 1

Comments

Your Answer

Sign up or log in

Post as a guest

Related