[boost] Re: "invariants" class; Version 1.02

From: Dan W. (danw_at_[hidden])
Date: 2004-01-10 21:52:59

Daniel Wallin wrote:
>> I filed a bug report. As for the macro, it was kind of needed anyways.
> Really? I'm referring to the INVARIANTS() macro, which wasn't needed in
> my code.

True, nor does my code really 'need' the macro...

#define INVARIANTS( name )   \
private:                     \
typedef name THIS_TYPE_NAME; \
friend struct                \
boost::DBC::EEICHK< name >;  \
void CHECK_INVARIANTS() const

...but I think it's kind of convenient.  You have a friend function, 
which you correctly declare private;  but if a user forgets to make it 
private it might cause hard to track problems. With the macro I'm 
forcing private, which might cause members below it to become private; 
but this shouldn't be as hard to debug.  What the problem with my 
compiler necessitates is the typedef, which in turn necessitates the 
name of the class as argument. Nothing I can do about it at the moment, 
as changing compilers is not an option for me. Long story.

Anyways, I think you have the same bug I have: A derived class can 
change its embedded base class' protected members or call its protected 
functions without causing base::check_invariants() to be called. I think 
that the solution is to make sure that a call of check_invariants in a 
derived class always implies a call of check_invariants in the base 
class or classes.  Not sure how I'm gonna tackle this one...

Cheers!