CODEWITHSUNDEEP
python
ealeon
ealeon

Reputation: 12452

python strings vs enum and how they are represented in memory level

zoo.py
from main import animal

def getAnimal(animal)
    1) if animal == animal.tiger:
    or
    2) if animal == "animal"

and

main.py
import Zoo        
Class animal
    tiger = "tiger"
    bear  = "bear"

1) get = Zoo.getAnimal(animal.tiger)
or
2) get = Zoo.getAnimal("tiger"):

The above is extremely basic example but what is the "best" convention of performing the above code?

I was told it is better to do it via 1) approach because "strange things happen due to how python uses pointers."

Whats happening in terms of at memory level when the above codes are executed?

If I remember correctly, each memory addr gets ascii value of char for the conseq allocated memory address for strings?

Is it the same when string is now being referenced as an object that of animal.tiger?

Or are there no differences at all?

Upvotes: 1

Views: 151

Answers (1)

Qiau
Qiau

Reputation: 6165

If the compiler doesn't optimize the code (i.e. it's more complex than your example) #2 will allocate an anonymous string with another pointer.

But since == do string compare it will work even if it is two different strings (in memory).

In your example the compiler will most likely optimize the code to be the same:

>>> class animal:
...  tiger = "tiger"
...  bear = "bear"
...
>>> animal.tiger
'tiger'
>>> id(animal.tiger)
140052399801616
>>> id('tiger')
140052399801616
>>>

EDIT: Added example of user input where string memory location differ:

>>> id(animal.tiger)
140052399801616
>>> a=raw_input()
tiger
>>> id(a)
140052399801664
>>> a==animal.tiger
True
>>> a is animal.tiger
False

(use is to compare objects in memory as above)

Upvotes: 2

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