From the previous question, what is the value of obj_outside.one after executing the `change` function?

Question

BlackTom AI · Accepted Answer

Rebinding a parameter inside a function does not modify the original object referenced by the caller, so obj_outside.one remains 1.

1. Relevant knowledge points and concepts
- Names (variables) in Python are references to objects. 
- Passing an object to a function copies the reference; both caller and parameter name initially reference the same object.
- Assignment to the parameter name (rebinding) makes that local name point to a new object; it does not change the caller’s reference.
- Mutating the object via the parameter (e.g., obj.one = 2 or modifying a list in-place) affects the original object and is visible to the caller.

2. Step-by-step reasoning
- Suppose before the call: obj_outside → ObjectA, and ObjectA.one == 1.
- Call change(obj_outside). Inside change, the parameter name obj initially refers to ObjectA as well.
- If the change function contains an assignment like obj = SomeNewObject or obj = AnotherClass(), this statement rebinds the local name obj to refer to a different object (ObjectB). That reassignment is local to the function.
- Any subsequent changes to obj after this rebinding affect ObjectB, not ObjectA.
- When the function returns, the local name obj is discarded; obj_outside in the caller still refers to ObjectA, whose attribute one was never mutated and remains 1.

3. Intermediate steps (reference flow)
- Before call: obj_outside -> ObjectA.one == 1
- On entry: obj (parameter) -> ObjectA
- Inside change: obj = ObjectB (rebinding)
- After function returns: obj_outside -> ObjectA.one == 1

4. Why the correct answer is correct
Because the function performed a local rebinding (not an in-place mutation of the original object), the attribute one of the original object was not changed. Only an in-place mutation (obj.one = value) would alter obj_outside.one.

5. Why other answers would be incorrect
- Any answer >1 (e.g., 2) would require the function to assign to obj.one or otherwise mutate ObjectA; that didn’t occur.
- None, 0, or an error would require different code paths (e.g., deleting the attribute, returning nothing and assigning, or raising exceptions), which are not the case given the behavior implied.

6. Conclusion
Therefore, obj_outside.one remains 1, matching the provided correct answer: 1.

From the previous question, what is the value of obj_outside.one after executing the `change` function? 数值题

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