Difference in handling of tuples in python shell vs IDLE

Question

I was learning about python tuples when I encountered a weird inconsistency. This code:

x = (1,2)
y = (1,2)
print(x is y)

This gives False in shell but True in IDLE. Is there a reason for that?

Good catch Fitz. I can confirm I see the same difference. Python 3.8. Strange — JD2775, Mar 10 '21 at 05:22
Python makes **no promises** about whether two equal (deeply) immutable values will be represented by the same object. Some cases get optimized. Some don't. Such optimizations are not part of the language definition and should not be relied upon. — user2357112, Mar 10 '21 at 05:23
`is` is used if both have same `id` i.e. referring to same object then true, use `==` — Epsi95, Mar 10 '21 at 05:24
I saw this recently: https://stackoverflow.com/questions/3718513/python-is-statement-what-is-happening — Kral, Mar 10 '21 at 05:25
a = 1, b=2-1, `a is b` `True`, I think it is upto interpreter logic to create new object or not — Epsi95, Mar 10 '21 at 05:27
@Epsi95 that is a particular CPython optimization that caches small `int` objects — juanpa.arrivillaga, Mar 10 '21 at 05:27

score -3 · Answer 1 · answered Mar 10 '21 at 05:42

-3

Actually Python IDLE and shell uses different storage system for data types like tuple-() All other data types like :

are goning to show the same.

answered Mar 10 '21 at 05:42

EpicPy

@Kral `is` and `==` are different. – EpicPy Mar 10 '21 at 05:43
1

"Actually Python IDLE and shell uses different storage system for data types like tuple" no, that is absolutely not true. – juanpa.arrivillaga Mar 10 '21 at 06:13
Ok then why please tell – EpicPy Mar 10 '21 at 06:17
There are many possible reasons, idle may be executing the whole block, where the peep-hole optimizer has optimized an immutable literal into being the same object, whereas in the shell, the blocks are separated, so the optimization doesn't happen. There are no "different storage systems" for specific data types in Python IDLE, that doesn't make any sense, IDLE is just an IDE, it isn't a separate runtime. – juanpa.arrivillaga Mar 10 '21 at 06:24

1 Answers1