[Python-3000] More uniform treatment of files' newlines attribute? (original) (raw)

skip at pobox.com skip at pobox.com
Sun Sep 23 23:07:02 CEST 2007

While editing the documentation of the builtin open function, I noticed that the newlines attributes can take on three different value types: None, strings or tuples of strings. It seems to me it would be better if was always a set containing the newline values seen so far. There's no testing necessary if you need to do something with the newlines you've seen, you just loop over them:

for nl in f.newlines:
    print("%r" % nl)

With the current mixed types metaphor you have to do something like this:

if f.newlines is not None:
    if type(f.newlines) is tuple:
        for nl in f.newlines:
            print("%r" % nl)
    else:
        print("%r" % f.newlines)

This, of course, assumes the file has been opened in text mode. If you have a binary mode file you also have to call hasattr(f, "newlines"). Presumably in most cases you'll know the file's mode without needing to check, but maybe binary files should also have a newlines attribute which is always the empty set.

Skip

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