Reason(原因)
make_shared gives a more concise statement of the construction. It also gives an opportunity to eliminate a separate allocation for the reference counts, by placing the shared_ptr's use counts next to its object.
make_shared为构造动作提供了更加简明的表达。由于它将shared_ptr的计数置于对象之后,使用它还可以提供减少另外一次的增加计数的机会。
Example(示例)
void test() {
// OK: but repetitive; and separate allocations for the Bar and shared_ptr's use count
shared_ptr<Bar> p {new Bar{7}};
auto q = make_shared<Bar>(7); // Better: no repetition of Bar; one object
}
原文链接:
https://github.com/isocpp/CppCoreGuidelines/blob/master/CppCoreGuidelines.md#c151-use-make_shared-to-construct-objects-owned-by-shared_ptrs
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