Creating boost::thread with an std::shared_ptr object instance

Question

I have the following two code segments. The first block compiles and works as expected. However the second block does not compile. My question is, given the code below what is the correct syntax when trying to create a thread based on an instance of an object that is being proxied by a shared_ptr? ``` #include #include #include #include struct foo { void boo() {} }; int main() { //This works { foo* fptr = new foo; boost::thread t(&foo::boo,fptr); t.join(); delete fptr; } //This doesn't work { std::shared_ptr fptr(new foo); boost::thread t(&foo::boo,fptr); t.join(); } return 0; } ``` The compiler error: ``` Error 5 error C2784: 'T *boost::get_pointer(T *)' : could not deduce template argument for 'T *' from 'std::tr1::shared_ptr<_Ty>' c:\program files (x86)\boost\boost_1_47\boost\bind\mem_fn_template.hpp 40 1 htest Error 3 error C2784: 'T *boost::get_pointer(const std::auto_ptr<_Ty> &)' : could not deduce template argument for 'const st…

Accepted Answer

The problem is that `boost::thread` relies on `boost::mem_fn` to handle member functions, and `boost::mem_fn` (or at least the version you are using) doesn't know how to use a `std::shared_ptr` to invoke a member function as it expects you to use `boost::shared_ptr` or one of the myriad of other smart pointer types in your error listing.

The raw pointer works because `boost::mem_fn` already has that overload. The solutions are to use `boost::shared_ptr` or `std::mem_fn`. The latter works because `std::mem_fn` knows how to interact with `std::shared_ptr`

`boost::thread t(std::mem_fn(&foo::boo), fptr);`

Creating boost::thread with an std::shared_ptr object instance

Solution

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