Effective Modern C++
42 SPECIFIC WAYS TO IMPROVE YOUR USE OF C++11 AND C++14
Scott Meyers
1. Deducing Types
Item 1:Understand template type deduction.
A function template is as looking like this:
template<typename T>
void f(ParamType param);
A call can look like this:
f(expr);
During compilation, compilers use
expr to deduce two types: one for
T and one for
ParamType.
Case 1: ParamType is a Reference or Pointer, but not a Universal Reference
template<typename T>
void f(T& param);
int x = 27; // x is an int
const int cx = x; // cx is a const int
const int& rx = x; // rx is a reference to x as a const int
the deduced types for
param and
T in various calls:
- f(x);
- f(cx);
- T is const int
- param is const int&
- f(rx);
- T is const int
- param is const int&
Case 2: ParamType is a Universal Reference
Case 3: ParamType is Neither a Pointer nor a Reference
Item 2:Understand auto type deduction.
Item 3:Understand decltype.
Item 4:Know how to view deduced types.
2. auto
Item 5: Prefer auto to explicit type declarations.
Item 6: Use the explicitly typed initializer idiom when auto deduces undesired types.
3. Moving to Modern C++
Item 7: Distinguish between () and {} when creating objects.
Item 8: Prefer nullptr to 0 and NULL.
Item 9: Prefer alias declarations to typedefs.
Item 10: Prefer scoped enums to unscoped enums.
Item 11: Prefer deleted functions to private undefined ones.
Item 12: Declare overriding functions override.
Item 13: Prefer const_iterators to iterators.
Item 14: Declare functions noexcept if they won’t emit exceptions.
Item 15: Use constexpr whenever possible.
Item 16: Make const member functions thread safe.
Item 17: Understand special member function generation.
4. Smart Pointers
Item 18: Use std::unique_ptr for exclusive-ownership resource management.
Item 19: Use std::shared_ptr for shared-ownership resource management.
Item 20: Use std::weak_ptr for std::shared_ptr-like pointers that can dangle.
Item 21: Prefer std::make_unique and std::make_shared to direct use of new.
Item 22: When using the Pimpl Idiom, define special member functions in the implementation file.
5. Rvalue References, Move Semantics, and Perfect Forwarding
Item 23: Understand std::move and std::forward.
Item 24: Distinguish universal references from rvalue references.
Item 25: Use std::move on rvalue references, std::forward on universal references.
Item 26: Avoid overloading on universal references.
Item 27: Familiarize yourself with alternatives to overloading on universal references.
Item 28: Understand reference collapsing.
Item 29: Assume that move operations are not present, not cheap, and not used.
Item 30: Familiarize yourself with perfect forwarding failure cases.
6. Lambda Expressions
Item 31:Avoid default capture modes.
Item 32:Use init capture to move objects into closures.
Item 33:Use decltype on auto&& parameters to std::forward them.
Item 34:Prefer lambdas to std::bind.
7. The Concurrency API
Item 35:Prefer task-based programming to thread-based.
Item 36:Specify std::launch::async if asynchronicity is essential.
Item 37:Make std::threads unjoinable on all paths.
Item 38:Be aware of varying thread handle destructor behavior.
Item 39:Consider void futures for one-shot event communication.
Item 40: Use std::atomic for concurrency, volatile for special memory.
8. Tweaks
Item 41: Consider pass by value for copyable parameters that are cheap to move and always copied.
Item 42: Consider emplacement instead of insertion.
留言