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- 1 Smart Pointers 101
- 2 The Deal
- 3 Storage of Smart Pointers
- 4 Smart Pointer Member Functions
- 5 Ownership Handling Strategies
- 6 The Address-of Operator
- 7 Implicit Conversion to Raw Pointer Types
- 8 Equality and Inequality
- 9 Ordering Comparisons
- 10 Checking and Error Reporting
- 11 Smart Pointers to const and const Smart Pointers
- 12 Arrays
- 13 Smart Pointers and Multithreading
- 14 Putting It All Together
- 15 Summary
- 16 SmartPtr Quick Facts
This chapter is from the book
This chapter is from the book
This chapter is from the book
This chapter is from the book
7.11 Smart Pointers to const and const Smart Pointers
Raw pointers allow two kinds of constness: the constness of the pointed-to object and that of the pointer itself. The following is an illustration of these two attributes4:
const Something* pc = new Something; // points to const object pc->ConstMemberFunction(); // ok pc->NonConstMemberFunction(); // error delete pc; // ok (surprisingly) Something* const cp = new Something; // const pointer cp->NonConstMemberFunction(); // ok cp = new Something; // error, can't assign to const pointer const Something* const cpc = new Something; // const, points to const cpc->ConstMemberFunction(); // ok cpc->NonConstMemberFunction(); // error cpc = new Something; // error, can't assign to const pointer
The corresponding uses of SmartPtr look like this:
// Smart pointer to const object SmartPtr<const Something> spc(new Something); // const smart pointer const SmartPtr<Something> scp(new Something); // const smart pointer to const object const SmartPtr<const Something> scpc(new Something);
The SmartPtr class template can detect the constness of the pointed-to object either through partial specialization or by using the TypeTraits template defined in Chapter 2. The latter method is preferable because it does not incur source-code duplication as partial specialization does.
SmartPtr imitates the semantics of pointers to const objects, const pointers, and the combinations thereof.