Sharing Ownership or Passing by Reference: A Dilemma with Shared Pointers
When working with shared pointers, developers often face a choice between passing them by reference or by value. While passing by reference may seem more performant, there are additional considerations to weigh before making a decision.
Understanding the Difference
Passing a shared pointer by reference means passing a pointer to the shared pointer itself, while passing by value means passing a copy of the shared pointer. Passing by reference allows the function to access the original shared pointer, while passing by value creates a new shared pointer that points to the same object.
Performance Considerations
Passing by reference does not require the creation of a copy, which could potentially save time and memory. However, this advantage can be outweighed if the function modifies the shared pointer, as this modification will persist outside of the function call.
Ownership Considerations
If the intent is to share ownership of an object with the function, then passing by reference is necessary. However, if the function only needs to access the object without modifying it, passing by value ensures that ownership remains with the calling code.
Recommended Practice
According to experts in the C community, there is generally no reason to pass a shared pointer by value. Passing by reference should be used unless the goal is to share ownership.
Conclusion
The decision of whether to pass a shared pointer by reference or by value depends on the specific requirements of the function. While passing by reference offers potential performance advantages, it should be used cautiously to avoid unexpected modifications to the shared pointer.
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