Question

I’m trying to understand the following piece of code:

lock_server::lock_server(class rsm *_rsm)
{
//code
}

I know that this is the constructor for the class, but I don’t understand its argument.
I’m guessing that this is a pointer (with name _rsm) that points to a class? Does that make sense? Where can I find documentation about this?

Answer 1

The keyword class before the term rsm is not necessary in C++ (unlike in C where you must specify the word struct).

However that doesn’t mean it is forbidden and whoever wrote that felt it was good style, albeit it’s intuitive that rsm is a type of some sort (not necessarily a class, could be a typedef to a class)

The purpose of that constructor is to construct an object of type lock_server with a pointer to a modifiable rsm object. My guess is that rsm has some kind of lock method which will be called from the constructor, and an unlock method which will be called from the destructor.

The purpose of the lock_server class is to implement what is called RAII: a stupid acronym but in real life it means automated resource management – when the object leaves scope the destructor kicks in which releases the resource it is holding, in this case a lock to the rsm object.