Re: Static initialization order

On 19/09/2013 07:41, DeMarcus wrote:


You are still missing the point. You seem to think that there is
some essential difference in C++ between a variable and an
object. If you want to define what you mean by an object that
distinguishes it from a variable we might then be able to have a
more meaningful dialogue.

The issue with globals is not about maintaining their internal
consistency but about the consequences of having them accessible
from many places in a program. That makes testing much harder and
more complex. It also makes predicting outcomes much harder.

Here is a simple example to highlight one of the problems

class object {
   // some suitable definition providing
   // all the possible benefits from
   // encapsulation
};

object obj{/* initialisation data */}

void foo(object const & o);

int main(){
   object obj1{obj}; // create a copy of the global
   foo(obj1);
   foo(obj); // call foo with the global
   std::cout << (obj == obj1 ? "X" : "Y") << std::endl; // A
}

What is the expected output? It is impossible to answer without
knowing the detail of foo()'s definition and the definitions of all
functions called by foo() (recursively) I.e. you need to know the
full details of the implementation of foo().

Here is a trivial definition of foo() that would generate 'Y' as
output:

void foo(object const & o){ obj.modify();}

// with modify changing the state of an instance of type object

Once we have a global non-const 'object' we have no certainty as to
its state once we call a function and pass it a reference or pointer
to that object.