[Python-Dev] bytes (original) (raw)

[Python-Dev] bytes / unicode

M.-A. Lemburg mal at egenix.com
Wed Jun 23 11🔞23 CEST 2010

Nick Coghlan wrote:

On Wed, Jun 23, 2010 at 4:09 AM, M.-A. Lemburg <mal at egenix.com> wrote:

It would be great if we could have something like the above as builtin method:

x.split('&'.as(x)) As per my other message, another possible (and reasonably intuitive) spelling would be: x.split(x.coerce('&'))

You are right: there are two ways to adapt one object to another. You can either adapt object 1 to object 2 or object 2 to object 1. This is what the Python2 coercion protocol does for operators. I just wanted to avoid using that term, since Python3 removes the coercion protocol.

Writing it as a helper function is also possible, although it be trickier to remember the correct argument ordering:

def coerceto(target, obj, encoding=None, errors='surrogateescape'): if isinstance(obj, type(target)): return obj if encoding is None: encoding = sys.getdefaultencoding() try:: convert = obj.decode except AttributeError: convert = obj.encode return convert(encoding, errors) x.split(coerceto(x, '&'))

Perhaps something to discuss on the language summit at EuroPython.

Too bad we can't add such porting enhancements to Python2 anymore. Well, we can if we really want to, it just entails convincing Benjamin to reschedule the 2.7 final release. Given the UserDict/ABC/old-style classes issue, there's a fair chance there's going to be at least one more 2.7 RC anyway. That said, since this kind of coercion can be done in a helper function, that should be adequate for the 2.x to 3.x conversion case (for 2.x, the helper function can be defined to just return the second argument since bytes and str are the same type, while the 3.x version would look something like the code above)

True.

Note that the point of using a builtin method was to get better performance. Such type adaptions are often needed in loops, so adding a few extra Python function calls just to convert a str object to a bytes object or vice-versa is a bit much overhead.

-- Marc-Andre Lemburg eGenix.com

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