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(C++) Class design

The design of a class.

Although entire books are written on this subject, here some guidelines from some experts:

• Follow a good method design
• Make interfaces easy to use correctly and hard to use incorrectly [1]
• Treat class design as type design [2]
• Prefer pass-by-reference-to-const to pass-by-value [3]
• Don't try to return a reference when you must return an object [4]
• Declare data members private [5][9][19][27], except in behaviourless aggregates (C-style structs) [19]
• Prefer non-member non-friend functions to member functions [6,22]
• Declare non-member functions when type conversion should apply to all parameters [7]
• Consider support for a non-throwing swap [8]
• Be clear what kind of class you're writing [10]
• Prefer minimal classes to monolithic classes [11]
• Prefer composition to inheritance[12]
• Avoid inheriting from classes that were not designed to be base classes [13]
• Prefer providing abstract interfaces [14]
• Public inheritance is substitutability. Inherit, not te reuse, but to be reused [15]
• Practive safe overriding [16]
• Consider making virtual functions nonpublic, and public functions nonvirtual [17]
• Avoid providing implicit conversions [18]
• Don't give away your internals [20]
• Pimpl judiciously [21]
• Always provide new and delete together [23]
• If you provide any class-specific new, provide all of the standard forms (plain, in-place, and nothrow) [24]

References

1. Scott Meyers. Effective C++ (3rd edition). ISBN: 0-321-33487-6. Item 18: Make interfaces easy to use correctly and hard to use incorrectly.
2. Scott Meyers. Effective C++ (3rd edition). ISBN: 0-321-33487-6. Item 19: Treat class design as type design.
3. Scott Meyers. Effective C++ (3rd edition). ISBN: 0-321-33487-6. Item 20: Prefer pass-by-reference-to-const to pass-by-value.
4. Scott Meyers. Effective C++ (3rd edition). ISBN: 0-321-33487-6. Item 21: Don't try to return a reference when you must return an object.
5. Scott Meyers. Effective C++ (3rd edition). ISBN: 0-321-33487-6. Item 22: Declare data members private.
6. Scott Meyers. Effective C++ (3rd edition). ISBN: 0-321-33487-6. Item 23: Prefer non-member non-friend functions to member functions.
7. Scott Meyers. Effective C++ (3rd edition). ISBN: 0-321-33487-6. Item 24: Declare non-member functions when type conversion should apply to all parameters
8. Scott Meyers. Effective C++ (3rd edition). ISBN: 0-321-33487-6. Item 25: Consider support for a non-throwing swap.
9. Herb Sutter, Andrei Alexandrescu. C++ coding standards: 101 rules, guidelines, and best practices. 2005. ISBN: 0-32-111358-6. Chapter 11: 'Hide information'.
10. Herb Sutter, Andrei Alexandrescu. C++ coding standards: 101 rules, guidelines, and best practices. 2005. ISBN: 0-32-111358-6. Chapter 32: 'Be clear what kind of class you're writing'.
11. Herb Sutter, Andrei Alexandrescu. C++ coding standards: 101 rules, guidelines, and best practices. 2005. ISBN: 0-32-111358-6. Chapter 33: 'Prefer minimal classes to monolithic classes'.
12. Herb Sutter, Andrei Alexandrescu. C++ coding standards: 101 rules, guidelines, and best practices. 2005. ISBN: 0-32-111358-6. Chapter 34: 'Prefer composition to inheritance'.
13. Herb Sutter, Andrei Alexandrescu. C++ coding standards: 101 rules, guidelines, and best practices. 2005. ISBN: 0-32-111358-6. Chapter 35: 'Avoid inheriting from classes that were not designed to be base classes'.
14. Herb Sutter, Andrei Alexandrescu. C++ coding standards: 101 rules, guidelines, and best practices. 2005. ISBN: 0-32-111358-6. Chapter 36: 'Prefer providing abstract interfaces'.
15. Herb Sutter, Andrei Alexandrescu. C++ coding standards: 101 rules, guidelines, and best practices. 2005. ISBN: 0-32-111358-6. Chapter 37: 'Public inheritance is substitutability. Inherit, not te reuse, but to be reused'.
16. Herb Sutter, Andrei Alexandrescu. C++ coding standards: 101 rules, guidelines, and best practices. 2005. ISBN: 0-32-111358-6. Chapter 38: 'Practive safe overriding'.
17. Herb Sutter, Andrei Alexandrescu. C++ coding standards: 101 rules, guidelines, and best practices. 2005. ISBN: 0-32-111358-6. Chapter 39: 'Consider making virtual functions nonpublic, and public functions nonvirtual'.
18. Herb Sutter, Andrei Alexandrescu. C++ coding standards: 101 rules, guidelines, and best practices. 2005. ISBN: 0-32-111358-6. Chapter 40: 'Avoid providing implicit conversions'.
19. Herb Sutter, Andrei Alexandrescu. C++ coding standards: 101 rules, guidelines, and best practices. 2005. ISBN: 0-32-111358-6. Chapter 41: 'Make data members private, except in behaviourless aggregates (C-style structs).
20. Herb Sutter, Andrei Alexandrescu. C++ coding standards: 101 rules, guidelines, and best practices. 2005. ISBN: 0-32-111358-6. Chapter 42: 'Don't give away your internals'.
21. Herb Sutter, Andrei Alexandrescu. C++ coding standards: 101 rules, guidelines, and best practices. 2005. ISBN: 0-32-111358-6. Chapter 43: 'Pimpl judiciously'.
22. Herb Sutter, Andrei Alexandrescu. C++ coding standards: 101 rules, guidelines, and best practices. 2005. ISBN: 0-32-111358-6. Chapter 44: 'Prefer writing nonmember nonfriend functions'
23. Herb Sutter, Andrei Alexandrescu. C++ coding standards: 101 rules, guidelines, and best practices. 2005. ISBN: 0-32-111358-6. Chapter 45: 'Always provide new and delete together'.
24. Herb Sutter, Andrei Alexandrescu. C++ coding standards: 101 rules, guidelines, and best practices. 2005. ISBN: 0-32-111358-6. Chapter 46: 'If you provide any class-specific new, provide all of the standard forms (plain, in-place, and nothrow)'.
25. Bjarne Stroustrup's C++ glossary: http://www.research.att.com/~bs/glossary.html#Gclass

26. C++. International Standard. ISO/IEC 14882. Second edition. Paragraph 14.1.2.
27. John Lakos. Large-Scale C++ Software Design. 1996. ISBN: 0-201-63362-0.

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