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Мутабельные и иммутабельные типы данныхИван Феофанов
apiqa.io
02
5
03
2
04
1
05
Immutable Mutable
int, float, complex list, set
tuple, frozenset dict
bytes bytearray
str
bool
Python data types
Immutable
a = 5
a 5
a += 2
a 7
id = 11197536
id = 11197568
b = a
b
06
WAT?
07
Mutable
a = [5, 10, 15]
a [5, 10, 15]
b = a
bid = 139872397262408
a += [20]
[5, 10, 15, 20]
08
Pitfalls
09
● default mutable arguments● side-effects
Default mutable argument
10
Default mutable argument: solution
11
PEP 505 -- None-aware operators (??=)
12
Side-effect
13
compile-time constant
Objects optimization
14
Mutable?
Create new object
Yes
Object type?
value in [-5...256]?
result of constant folding
int
stringNo
No
Refer to existing object
Yes
Yes
object length > 20?No
Yes
No
Yes
contains only ASCII letters, digits or underscores
No No
Yes
bonus
+=
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