Pointers and References

1. Pointers and
References
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2. Concepts
• Pointers
• References (in C++ and other environment)
• Lifetime and Ownerships
• Copy and Move

3. Terms
1. Pointers is object addresses
2. (C++) Reference is name alias
3. Java uses reference semantics
4. Java object is passed by reference

4. Pointers
• Pointer (or reference) is an proxy object which
refers to another object indirectly.

5. Pointers
• Pointer (or reference) is an proxy object which
refers to another object indirectly.

6. Pointers (in C)
• Object ID (maybe memory address)
• Object Type

7. Why we need pointer?

8. Issues with C Pointers
• Dangling Pointers
• Resource Leaks
• Null Pointers
• Weak-typed

9. References
• (C++)Reference was an simple syntax sugar of
pointers at first.

10. References
• Reference is a **SAFE**
pointer
• Must be initialized
• Can’t be re-binded
• Can’t be null

11. Pass By Reference

12. Reference other than C++
• Java / C#:
• Value & Reference semantics
• Automatic resource management
• Python / JS:
• Everything is reference
• CoW
• Automatic resource management

13. Copy on Write

14. Issues with Reference Semantics
• Resource management & Lifetime control

15. Object Lifetime
• Global / static object
• Local object
• Dynamically created object
• Program data (Constant pool etc.)

16. Resource Binding Strategy
• Heap object with GC
• Stack object with RAII
• Unique Ownership

17. Unique Ownership
• If owner of resources is destroyed, ALL RESOURCE it
owned would be released
• Ownership should be unique

18. Unique Ownership

19. Move semantics

20. Move semantics
• Zero-copy
• Resource uniqueness

21. Borrowing

22. Reference Model
• Semantics
• Value Semantics
• Reference Semantics
• Move Semantics
• Ownership
• Borrowing