Locking data

[IntegratedDimensions]

an idea to lock data by removing the reference:

class A
{
    Lockable!Data data;
}

The idea is that when the data is going to be used, the user 
locks the data. The trick here is that data is a pointer to the 
data and the pointer is set to null when locked so no other data 
can use it(they see a null reference). To unlock, the data is 
reassigned:

auto d = data.lock(); // A.data is now null deals with sync issues
//use d
d = data.unlock(d); // restores A.data (A.data = d;) and sets d 
to null so any future reference is an error(could produce bugs 
but should mostly be access violations)


Anyone else trying to use data will see that it is null while it 
is locked.

This basically pushes the standard locking mechanisms in to the 
Lockable!data(first come first serve) and code that has not 
captured the data see's it simply as null.

Anyone use know if there exists an idiom like this and what it is 
called? Maybe some idiomatic code that is efficient?


Ideally I'd want to be able to treat the Lockable!Data as Data. 
Right now I have to classes(or pointers to structs) and few weird 
hacks. I think what I'll have to end up doing is having a 
Locked!Data structure that is returned instead or use an UFCS. 
The idea being to attach the lock and unlock methods.