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Ownership Types, Views and Type Erasure · 3:48
make_unique and make_shared
Why the standard library would rather call new for you. make_unique and make_shared name the type once, make sure the object is owned before anything can throw (we force a bad_alloc to watch emplace_back(new W) leak), and make_shared fuses the object and its control block into one allocation, which we measure on a Mac. The cost: that fused block stays allocated until the last weak_ptr is gone, and the make functions can't take custom deleters or braces.
You will learn
- Explain the three reasons to prefer make_unique and make_shared
- Show how a raw new passed to emplace_back can leak when the vector's growth throws
- Describe make_shared's single fused allocation and its cost when weak_ptrs outlive the object
- Recognise when you still need new: custom deleters and braced initializers