[David Beazley, pretty much repeats why he doesn't like the current scheme]
I hoped it was clear the first time I was at least half sympathetic! If it
wasn't, I am <wink>.
>> >>> i = 12
>> >>> (lambda: [i**2 for i in range(4)])()
>> [0, 1, 4, 9]
>> >>> i
>> 12
>> >>>
>>
>> That's more like Haskell does it.
> Ah yes, well this is exactly the kind of behavior that seems most
> natural to me. It's also the behavior that everyone expected went I
> went around to the various Python hackers in the department and asked
> them about it yesterday.
I believe that.
> I suppose I could just write this:
>
> a = (lambda s: [2*i for i in s])(s)
>
> However, that's pretty ugly.
It's too complicated, isn't it? In the presence of nested scopes (which are
reality in 2.2),
a = (lambda: [2*i for i in s])()
does the same thing and is conceptually clearer. I'm not suggesting that
you actually write that, but view it as a *model* for your intended
semantics. I wouldn't want to see the implementation actually use a lambda
under the covers, either, but we need some crisp way to explain the intent.
Note that the lambda-trick *model* "does the right thing" for for-loop
targets like x.i and x[i] too.
> In any case, I'm mostly just curious if anyone else has been bitten by
> the problem I've described. I would certainly love to see a fix for
> it (I would even volunteer to work on a prototype implementation if
> there is interest).
I encourage that, but since it's not 100% backward-compatible you'll enjoy
the usual range of hysterical <wink> opposition. Needs a PEP, and possibly
even an associated future-statement. Overall, I'm more in favor of changing
it than not.
RetroSearch is an open source project built by @garambo | Open a GitHub Issue
Search and Browse the WWW like it's 1997 | Search results from DuckDuckGo
HTML:
3.2
| Encoding:
UTF-8
| Version:
0.7.4