On 3/25/2014 8:07 AM, Antoon Pardon 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?
It is quite possible that the print change broke more than the dict
change would have. The difference is that the print statement syntax was
both awful and limited. The print function uses standard syntax and is
more flexible.
The fact that print could be turned into a function shows that it did
not need to be a statement. All other simple statements except 'pass'
either implicitly quote an expression in the statement, jump control, or
declare something to the compiler.
The other fact that Chris noted, that '{}' would have been valid but
with different meanings in Py1/2 versus Py3, was a factor on the cost
side. We generally try to avoid such ambiguities.
Except for this last point, I was in favor of the switch.
--
Terry Jan Reedy
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