Hi, Builtin open() function is unable to open an UTF-16/32 file starting with a BOM if the encoding is not specified (raise an unicode error). For an UTF-8 file starting with a BOM, read()/readline() returns also the BOM whereas the BOM should be "ignored".
See recent issues related to reading an UTF-8 text file including a BOM: #7185 (csv) and #7519 (ConfigParser). Such file can be opened in unicode mode with the UTF-8-SIG encoding, but it's possible to do better. I propose to improve open() (TextIOWrapper) by using the BOM to choose the right encoding. I think that only files opened in read only mode should support this new feature. *Read* the BOM in a *write* only file would cause unexpected behaviours. Since my proposition changes the result TextIOWrapper.read()/readline() for files starting with a BOM, we might introduce an option to open() to enable the new behaviour. But is it really needed to keep the backward compatibility? I wrote a proof of concept attached to the issue #7651. My patch only changes the behaviour of TextIOWrapper for reading files starting with a BOM. It doesn't work yet if a seek() is used before the first read. -- Victor Stinner http://www.haypocalc.com/ _______________________________________________ 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
