Welcome to OGeek Q&A Community for programmer and developer-Open, Learning and Share
Welcome To Ask or Share your Answers For Others

Categories

0 votes
374 views
in Technique[技术] by (71.8m points)

c++ - Are there any downsides with using make_shared to create a shared_ptr

Are there any downsides with using make_shared<T>() instead of using shared_ptr<T>(new T).

Boost documentation states

There have been repeated requests from users for a factory function that creates an object of a given type and returns a shared_ptr to it. Besides convenience and style, such a function is also exception safe and considerably faster because it can use a single allocation for both the object and its corresponding control block, eliminating a significant portion of shared_ptr's construction overhead. This eliminates one of the major efficiency complaints about shared_ptr.

See Question&Answers more detail:os

与恶龙缠斗过久,自身亦成为恶龙;凝视深渊过久,深渊将回以凝视…
Welcome To Ask or Share your Answers For Others

1 Reply

0 votes
by (71.8m points)

In addition to the points presented by @deft_code, an even weaker one:

  • If you use weak_ptrs that live after all the shared_ptrs to a given object have died, then this object's memory will live in memory along with the control block until the last weak_ptr dies. In other words the object is destroyed but not deallocated until the last weak_ptr is destroyed.

与恶龙缠斗过久,自身亦成为恶龙;凝视深渊过久,深渊将回以凝视…
OGeek|极客中国-欢迎来到极客的世界,一个免费开放的程序员编程交流平台!开放,进步,分享!让技术改变生活,让极客改变未来! Welcome to OGeek Q&A Community for programmer and developer-Open, Learning and Share
Click Here to Ask a Question

...