Krita/C++11
General links to about using C++11
There have been a few links discussing mixing C++11 with Qt, and starting with Qt 5.6 C++11 support will be default. Note: as would be expected from those interested in hot new technology, the writers of most of these links demonstrate Silicon Valley levels of extreme optimism. Take this with a grain of salt: there is no such thing as a free lunch.
- ICS.com
- qt.io
- woboq.com: c++11 in Qt5
- woboq.com: c++14 in Qt5
- FOSDEM 2013 presentation slides
- Bjarne Stroustrup's C++11 FAQ - the grand daddy
Particular Features
Under "drawbacks," every item should list: "Programmers will face another feature they must learn about."
Type Inference (auto)
Motivation:
Drawbacks:
Recommendation:
Range-based for loop
Motivation:
Drawbacks: Warning: c++11 range-based for may be slower
Recommendation:
General Initializer Lists
Motivation: Member Initializers Mixed uniform initialization
Drawbacks:
Recommendation:
Lambdas
Motivation: Lambda expressions for slots "C++11 lambdas are your friend"
Drawbacks:
Recommendation:
constexpr
Motivation: Can speed things up inside hot loops. KDAB: speed up your Qt 5 programs using C++11
Drawbacks:
Recommendation:
Override and final
Motivation:
Drawbacks:
Recommendation:
<algorithm>
Motivation:
Drawbacks:
Recommendation:
enum class
Motivation:
Drawbacks:
Recommendation:
nullptr
Motivation:
Drawbacks:
Recommendation:
Deleted and default class members
Motivation:
Drawbacks:
Recommendation:
unique_ptr
Motivation:
Drawbacks: unique_ptr is unable to be copied, and therefore cannot be used inside Qt classes. For example QVector<std::unique_ptr> is invalid, because QVector requires its members can be copied. This makes converting to unique_ptr a bit slow, since QVector<T *> will have to be converted to std_array<unique_ptr<T*>>. If the owner was being copied before, it will become uncopiable. This can be a good thing, but it is work.
Recommendation:
Using move constructors and rvalues are very subtle and advanced features, but widely celebrated as successes of C++11. In general these should be used inside hot paths and when we sling around objects from place to place. C++ programmers should already be aware that writing performant code inside hot paths will sometimes require slinging around ampersands. These features will naturally stay confined to the corners of the codebase where they belong, and should be introduced when they are useful.
Move Constructors
Motivation:
Drawbacks:
Recommendation:
Reference Qualifiers
Motivation:
Drawbacks:
Recommendation:
C++11 features mostly for template programming
Krita makes very light use of templates. These features are useful, coming across them in the code base will add complexity for new learners, and have not been necessary so far.
- decltype
- static_assert
- std::function and std::bind
- variadic templates
Other C++11 features that probably cannot be used
- Threads (Qt/KDE use an incompatible threading model)
- shared_ptr and weak_ptr (Relies on C++ threading model; use KisSharedPointer)
- New literal types (already have QString)
- Extended Unions (already have QVariant)