FeedaMail: Comments for Sutter’s Mill

	Comments for Sutter's Mill
	(Sponsor this newsletter) Comment on GotW #91 Solution: Smart Pointer Parameters by Bret Kuhns @CS There was a proposal for this for C++1y, but didn’t make it into the draft. I believe the reasoning was that in the presence of `std::shared_ptr` and `std::unique_ptr`, raw points should always be expressed as observing. Unfortunately, your example of legacy code is exactly the reason why this was a bad decision. I would love to see the “worlds dumbest smart pointer” get revisited in the general library TS coming after C++14… http://www.open-std.org/jtc1/sc22/wg21/docs/papers/2013/n3514.pdf Read More » Comment on GotW #94 Solution: AAA Style (Almost Always Auto) by void* We have been trying to define a good strategy for the use of auto for a customer’s C++11 guidelines. Researching we found these nice three GotWs about auto. :) Thanks for those! Trying to consequently use auto for local variables we ran into three situations where it does not work nicely: #include <vector> class foo_t { public: foo_t() {} foo_t( const foo_t& ) = delete; void bar() const {} }; int main() { // example 1: doesn't work for pointer types // auto i_ptr = int*{}; // like this it's fine typedef int* int_ptr_t; auto i_ptr_2 = int_ptr_t{}; // example 2: doesn't work for non-copyable classes // compiles with VS2013, but I think it shouldn't (g++ doesn't like it) //auto foo = foo_t{}; // example 3: auto does worse than manually written code can std::vector< foo_t* > foo_ptrs; // foo is not as const as it could be (only foo_t* const, could be const foo_t* const) for( const auto foo : foo_ptrs ) { foo->bar(); } // better because it's "more" const for( const foo_t* const foo: foo_ptrs ) { foo->bar(); } } - The pointer example is an edge case. Probably don’t need this very much in C++-code (and there’s a work around). - Having non-copyable objects is more relevant though. I regularly see that…probably thanks to Scott Meyers (Effective C++, Item 6: Explicitly disallow the use of compiler-generated functions you do not want). - The third situations occurs quite often in legacy code and it just runs against Effective C++, Item 3: Use const whenever possible Any thoughts/comments about these three cases? Best regards Wolfgang Petroschka Read More »
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