On 7/30/07, [EMAIL PROTECTED] <[EMAIL PROTECTED]> wrote: > I was looking at PEP 3116 to try and figure out what the newline keyword > argument was for (it was mentioned in a couple replies to some checkin > comments and I see it in io.py). It's not really mentioned in the PEP as > far as I could tell other than this: > > Some new features include universal newlines and character set encoding > and decoding. > > The io.open() docstring has this to say: > > newline: optional newlines specifier; must be None, '\n' or '\r\n'; > specifies the line ending expected on input and written on > output. If None, use universal newlines on input and > use os.linesep on output. > > Shouldn't '\r' be provided as an option for Macs? Also, shouldn't the "U" > mode flag be discarded (2to3 could maybe do this)? Is this particular bit > of backwards compatibility all that necessary?
I don't think \r needs to be supported -- OSX uses \n; Python 3.0 isn't going to be ported to MacOS 9. We discussed this before; I promised I'd add \r support if anyone can find a current use case for it. So far none have been reported. Regarding dropping 'U': agreed. But since the fixer hasn't been written yet it hasn't been dropped yet. We need help for little niggling details like this! > The other thing I wanted to comment on is the default value for n in the > various read methods. In some places it's -1 (why not zero? *), but in > other places it's None, with presumably the same meaning. Shouldn't this be > consistent across all read methods? The couple read methods mentioned in > PEP 3116 only mention n=-1 as a default. > > Skip > > (*) A few days ago at work I saw someone check in a piece of code with > > f.read(-1) > > That looked so strange to me I had to look up its meaning. I don't think I > had ever seen someone explicitly call read with a -1 arg. read(0) means to read zero bytes. It always returns an empty string (or byte array). There are plenty of end cases where this is useful. read(), read(None) and read(-1) are all synonyms, meaning "read until EOF". The reason there are three spellings is mostly historic; because there are so many different file-like objects and not all of them implemented this consistently. Since the argument is an integer, it's the easiest to use -1 as the default; but since some classes used None as the default instead, some people started *passing* None, and then the need was born to support both. Arguably this was a bad idea, and we should add a new API readall() (one of the implementations already has this, and read(-1) calls it). Then the 2to3 fixer will have to recognize this. I welcome patches! But right now, getting the number of failing unit tests in the py3k-struni branch down to zero is more important. To help, see http://wiki.python.org/moin/Py3kStrUniTests. -- --Guido van Rossum (home page: http://www.python.org/~guido/) _______________________________________________ Python-3000 mailing list Python-3000@python.org http://mail.python.org/mailman/listinfo/python-3000 Unsubscribe: http://mail.python.org/mailman/options/python-3000/archive%40mail-archive.com
