Menu
As output from one function, I get an object of type Foo. As an argument to another class, I need to pass an object of type std::shared_ptr<Foo>. How can I make the shared pointer from the original object?
773
The weak_ptr class template stores a "weak reference" to an object that's already managed by a shared_ptr. To access the object, a weak_ptr can be converted to a shared_ptr using the shared_ptr constructor or the member function lock.
Use unique_ptr when you want to have single ownership(Exclusive) of the resource. Only one unique_ptr can point to one resource. Since there can be one unique_ptr for single resource its not possible to copy one unique_ptr to another. A shared_ptr is a container for raw pointers.
Pass the shared_ptr by value. This invokes the copy constructor, increments the reference count, and makes the callee an owner. There's a small amount of overhead in this operation, which may be significant depending on how many shared_ptr objects you're passing.
The ownership of an object can only be shared with another shared_ptr by copy constructing or copy assigning its value to another shared_ptr . Constructing a new shared_ptr using the raw underlying pointer owned by another shared_ptr leads to undefined behavior.
This is really quite simple:
auto val = std::make_shared<Foo>(FuncThatReturnsFoo(...));
Basically, just heap allocate a new Foo, copying/moving the result into it.
183
If you love us? You can donate to us via Paypal or buy me a coffee so we can maintain and grow! Thank you!
Donate Us With
