On Tue, Mar 25, 2014 at 11:07 PM, Antoon Pardon
<antoon.par...@rece.vub.ac.be> wrote:
> On 25-03-14 12:12, Chris Angelico wrote:
>
>> On Tue, Mar 25, 2014 at 9:24 PM, Antoon Pardon
>> <antoon.par...@rece.vub.ac.be> wrote:
>>> No they didn't have to. With the transition to python3, the developers
>>> could have opted for empty braces to mean an empty set. And if they
>>> wanted a literal for an empty dictionary, they might have chosen {:}.
>>> Backward-compatibility was already broken so that wasn't an argument.
>> Python 3.0 didn't just say "to Hades with backward compatibility". The
>> breakage was only in places where it was deemed worthwhile. Changing
>> the meaning of {} would have only small benefit and would potentially
>> break a LOT of programs, so the devs were right to not do it.
>
> More programs than those who broke because print was now a function?
> Do you think it would have been so problamatic that it couldn't have
> been handled by '2to3'?
It makes the same notation mean different things, in ways that are
hard to render clearly. You can write a Py3 program and put this at
the top for Py2:
try:
input = raw_input
range = xrange
except NameError:
# We're running on Python 3
pass
But you can't do the same for braces. You'd have to eschew *both*
literal-ish notations and use explicit constructors everywhere. Not
clean.
ChrisA
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