[Python-ideas] frozenset literals

[Hua Lu]

Perhaps, but we'd have to be careful with how we introduce those symbols:

http://nedbatchelder.com/blog/201206/eval_really_is_dangerous.html

You could possibly not allow attribute access but permit those
symbols... is there an exploit possible with that much filtering?

On Sat, Feb 2, 2013 at 12:30 PM, MRAB <python at mrabarnett.plus.com> wrote:
> On 2013-02-02 14:28, Antoine Pitrou wrote:
>>
>> On Sun, 03 Feb 2013 01:20:38 +1100
>> Steven D'Aprano <steve at pearwood.info> wrote:
>>>
>>>
>>> Unfortunately the proposal to use f{ ... } for frozen sets cannot work
>>> within the constraints of Python's lexer:
>>>
>>> http://mail.python.org/pipermail/python-3000/2008-January/011838.html
>>>
>>> Unfortunately we're running out of useful, easy to enter symbols for
>>> literals. Until such time (Python4000 perhaps, or more likely Python5000) as
>>> we can use a rich set of Unicode literals, I don't think there is any clear
>>> way to have a frozenset literal.
>>
>>
>> I'm not sure what the point is. frozensets are too rarely used to
>> deserve a literal notation.
>>
> Does it need a special notation as such?
>
> Wouldn't an alternative be to support "frozenset(...)" where "..." is
> parseable by ast.literal_eval()?
>
> The same thing could be done with some other built-in classes.
>
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