Passing reference data to class and incapsulation

[Uranuz via Digitalmars-d-learn]

In D we a several data types which are passed by reference: 
dynamic arrays, associative arrays. And sometimes we need to pass 
these reference data to class instance to store it inside. One of 
the principles of object-oriented programming is incapsulation. 
So all class data should be only modyfiable via class methods and 
properties. But I we pass reference data to class (for example as 
parameter in constructor) we still can change these data from 
initial code and break some internal logic of class for modifying 
these data. Example:

class Foo {
     this(int[] b) { bar = b; }
     private int[] bar;
     //Some methods
}

void main() {
     int[] bar = [1,2,3,4,5];
     Foo foo = new Foo(bar);
     //There I could do some logic with class
     bar[2] = 6; //I modify class without some checks from class
     //And there I might pass *bar* somewhere outside and break 
incapsulation
}

Same situation happens when I assign reference data to 
properties. I can check or do something with data at the moment 
of assignment, but I can't control that someone will modify using 
initial reference from outside. So do you copy reference data in 
constructors or properties? Should it be? Or call site should be 
responsible for not escaping reference somewhere outside and not 
modifying these data badly?

There also possible some situations when these data should be 
shared between different pieces of code (for example different 
class instance could reference the same memory area). But I think 
this is not very good and safe approach and should be avoided if 
possible.

But I think storing reference to class inside another class could 
be good approach because there could be different type of 
relations between classes. For plain data types we often have 
types of relations: *ownership* or *aggregation*. But classes can 
usualy have more types of relations: *usage* or when one class 
subscribes for events of another.

Is there some good links to read for these questions that you 
could advice. After several hours of googling I haven't found 
good topics about these problems. And I have not enough time for 
reading big book.