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Is it safe to use cv::Ptr<> within STL containers?

asked 2013-02-05 08:23:15 -0500

SR gravatar image

AFAIK std::auto_ptr<> is not suitable for STL containers.

Is it safe to use cv::Ptr<> within STL containers e.g. as std::vector< cv::Ptr<MyObject> >?

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answered 2013-02-05 10:20:25 -0500

sammy gravatar image

updated 2013-02-06 04:55:01 -0500

The auto_ptr<> template has a number of issues, that make it unsuitable for a range of applications.

However, the cv::Ptr<> class is a full-fledged smart-pointer template, similar to boost::shared_ptr<>. You can use it safely in containers, and with some care and limitations, across threads.

Here is a more detailed explanation on smart pointers

http://answers.opencv.org/question/535/is-there-penalty-for-reference-counting-in-mat/#538

Update on thread safety

(Copied from boost library docs - cv::Ptr<> and boost::shared_ptr<> are very similar in construction and usage)

shared_ptr objects offer the same level of thread safety as built-in types. A shared_ptr instance can be "read" (accessed using only const operations) simultaneously by multiple threads. Different shared_ptr instances can be "written to" (accessed using mutable operations such as operator= or reset) simultaneosly by multiple threads (even when these instances are copies, and share the same reference count underneath.)

Any other simultaneous accesses result in undefined behavior.

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Thank you, could you please elaborate on "with some care and limitations". What do you mean exactly?

SR gravatar imageSR ( 2013-02-06 01:57:51 -0500 )edit

Updated answer

sammy gravatar imagesammy ( 2013-02-06 04:55:52 -0500 )edit

Thank you!

SR gravatar imageSR ( 2013-02-06 06:41:27 -0500 )edit
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Asked: 2013-02-05 08:23:15 -0500

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Last updated: Feb 06 '13