What is a mutable operation?

[anonymous23323124]

I was reading about the thread safey of boost::shared_ptr, and it said the following:

A shared_ptr instance ... can be "written to" (accessed using mutable operations such as operator= or reset) simultaneosly by multiple threads

I know what the mutable keyword does to a member variable in C++. But what is a mutable operator?

[Athar]

There's no deeper meaning. A mutable operation is one that changes the object (one or several members).