Dino Viehland wrote: > We ran into an interesting user-reported issue w/ IronPython and the way > Python writes to files and I thought I'd get python-dev's opinion. > > When writing a string in text mode that contains \r\n we both write \r\r\n > because the default write mode is to replace \n with \r\n. This works great > as long as you stay within an entirely Python world. Because Python uses \n > for everything internally you'll never end up writing out a \r\n that gets > transformed into a \r\r\n. But when interoperating with other native code > (or .NET code in our case) it's fairly easy to be exposed to a string which > contains \r\n. Ultimately we see odd behavior when round tripping the > contents of a multi-line text box through a file. > > So today users have to be aware of the fact that Python internally always > uses \n. They also need to be aware of any APIs that they call that might > return a string with an embedded \r\n inside of them and transform the string > back into the Python version. > > It could be argued that there's little value in doing the simple > transformation from \r\n -> \r\r\n. Ultimately that creates a file that has > line endings which aren't good on any platform. On the other hand it could > also be argued that Python defines new-lines as \n and there should be no > deviation from that. And doing so could be considered a slippery slope, > first file deals with it, and next the standard libraries, etc... Finally > this might break some apps and if we changed IronPython to behave differently > we could introduce incompatibilities which we don't want. > > So I'm curious: Is there a reason this behavior is useful that I'm missing? > Would there be a possibility (or objections to) making \r\n be untransformed > in the Py3k timeframe? Or should we just tell our users to open files in > binary mode? :) >
It is normal when working with Windows interaction in the Python world to be aware that you might receive strings with '\r\n' in and do the conversion yourself. We come across this a great deal with Resolver (when working with multi line text boxes for example) and quite happily replace '\r\n' with '\n' and vice versa as needed. As a developer who uses both Python and IronPython I say that this isn't a problem. I may be wrong or outvoted of course... Michael http://www.manning.com/foord > _______________________________________________ > Python-Dev mailing list > Python-Dev@python.org > http://mail.python.org/mailman/listinfo/python-dev > Unsubscribe: > http://mail.python.org/mailman/options/python-dev/fuzzyman%40voidspace.org.uk > > _______________________________________________ Python-Dev mailing list Python-Dev@python.org http://mail.python.org/mailman/listinfo/python-dev Unsubscribe: http://mail.python.org/mailman/options/python-dev/archive%40mail-archive.com
