Information Regarding const_cast on DataMembers

Hi,

We had a discussion on this board regarding the usefulness of const_cast.

"if a variable is const at its point of definition, the result of
casting it away are undefined".

Polymorphic OOP suggested that this rule might not be applicable on non-static const datamembers.

Below mentioned is the extract of the email-interaction between "Bjarne Stroustrup" and me

---------------- My Question --------------------
Sir,
You have suggested that

const int i = 10;

int *p = const_cast<int *>(&i);

*p = 20; // Result is undefined

"if a variable is const at its point of definition, the result of
casting it away are undefined".

My question is "are datamembers an exception to to this suggestion?"
---------------------------My Question Ends Here ---------------

-------------- Bjarne Stroustrup's Answer ----------------------

No, and it's not a "suggestion" its a rule of the language. An
implementation is allowed to place a const in unwritable memory, such as a code segment, so that the *p=20 causes a run-time hardware exception. This is sometimes done in embedded systems where RAM is scarce and ROM cheaper.

-------------- Bjarne Stroustrup's Answer Ends Here--------------


Hope this is of some help to you folks