On Tue, Mar 25, 2008 at 5:06 PM, Adam Olsen <[EMAIL PROTECTED]> wrote:
> On Tue, Mar 25, 2008 at 2:43 PM, Alexander Belopolsky
>
> <[EMAIL PROTECTED]> wrote:
>
> > On Tue, Mar 25, 2008 at 4:26 PM, Adam Olsen <[EMAIL PROTECTED]> wrote:
>
> > > It does not even have to be a frozenset. A set works just as well,
> > > never modified by the produced bytecode.
> >
> > With the current implementation, precomputed constants must be
> > hashable because the compiler uses a dictionary lookup in order to
> > eliminate duplicates. This is of course just an implementation
> > detail, but it would actually be hard to work around it.
>
> Only builtin types with literal syntax may be deemed "constant"
> anyway. I fail to see how that's relevant to my frozenset vs set
> comment.
I realized that right after I hit the "send" button, so my comment
about optimizing
frozenset({...}) was wrong. With respect to frozenset vs set comment,
I understand
your proposal as transforming current
>>> dis(lambda: i in {1,2,3})
1 0 LOAD_GLOBAL 0 (i)
3 LOAD_CONST 0 (1)
6 LOAD_CONST 1 (2)
9 LOAD_CONST 2 (3)
12 BUILD_SET 3
15 COMPARE_OP 6 (in)
18 RETURN_VALUE
to
1 0 LOAD_GLOBAL 0 (i)
3 LOAD_CONST 3 ({1, 2, 3})
6 COMPARE_OP 6 (in)
9 RETURN_VALUE
This will not work because {1, 2, 3} is not hashable, but it should be
possible to do
1 0 LOAD_GLOBAL 0 (i)
3 LOAD_CONST 3 (frozenset({1, 2, 3}))
6 COMPARE_OP 6 (in)
9 RETURN_VALUE
On the other hand, our dialog is increasingly off-topic. My original
question was whether or not it will be a good idea to unify how set
and dict literals are processed. Please comment on the following
options:
1. Do nothing: dicts are built incrementally, and sets in batch.
2. Implement batch processing for dict literals.
3. Implement incremental processing for sets.
My order of preference is 2, 1, 3.
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