On May 16, 2008, at 3:23 AM, Stefan Behnel wrote:
> Hi,
>
> Robert Bradshaw wrote:
>> I would rather that string literals be interpreted according to the C
>> library they're linked against. I'm also thinking about code that,
>> say, returns string literals. I would much rather it returns str in
>> Py2 and unicode in Py3.
>
> That would be unexpected, especially in Py3 where the two are
> distinct types.
They are two distinct types in Py2 as well. (Well, str is being
renamed to bytes, and unicode to str?)
> As I said to Lisandro in another post:
>
> S> If you want source compatibility, you can't change the semantics
> based on
> S> the compile time environment - except for the cases where the
> runtime
> S> environments really differ (such as byte/unicode identifiers).
> Imagine you
> S> had some latin-1 encoded XML byte literal in your code. In Py2,
> under your
> S> proposal, this would become a byte string that can be parsed. In
> Py3,
> S> however, this would suddenly become a unicode string and the
> parser would
> S> refuse to handle it, as it's no longer ISO encoded.
Yes, I saw this. I don't see how this is an issue--due to your work
implementing PEP 263 any string literal has a well-defined unicode
meaning.
>> Note, this is not something that needs to be done to get ready for
>> Py3--it's an assumption that unqualified string literals are the same
>> type as python identifiers.
>
> This happens to be a correct assumption in Py2 and Py3, but I don't
> see the link.
>
>
>> I was doing some playing around with str and unicode in Python, and I
>> noticed that it will automatically convert between the two (no
>> explicit encoding needed) as long as the data in question is pure
>> ASCII.
>
> That would be Py2. Py3 will never attempt any kind of automatic
> conversion
> between bytes and str. And I am convinced that Cython shouldn't do
> that either.
I haven't played with Py3. I was actually (pleasantly) surprised it
worked in Py2, but if it's being discontinued then it doesn't help my
case. But it does mean that stuff like
--- a.pyx ---
def foo(x):
if x > 0:
return "good"
else:
return "bad"
-------------
import a
print "3 is %s" % a.foo(3)
won't work in both Py2 and Py3, which I think it should. "Principle
of least surprise."
- Robert
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