const is a terrible cancer and should be stopped in its tracks! 

so, in C++, there is an infectious storage class modifier called const. const is evil because it spreads unstoppably through code. Have a class with a const member? have to ever pass it as an argument to a function (oh, sorry, they call those methods now)? well you'll have to pass it in as const (and of course mangle your function in the process).. Can't mutilate the function (like say it doesnt belong to you)? well sorry, you can't cast out of const-ness (const_cast kind of works but will sometimes not). One of the most evil aspects of const is that it infects any clean C code that you might be trying to compile or even link into a c++ program. (why on earth would one want to keep as much of the code as possible as clean simple C, we will leave as an exercise for the reader :-) Need to work around this lunacy? quite simple! the compiler is clever, but not clever enough to see through unions! (or any other equivalent pointer wankery that could get a normally declared pointer pointing at the same location as a const one) It has the slight advantages over simple pointer wankery that unions are much more portable, a good bit more transparent to a human reading the code, and don't/shouldn't open the door for any other compiler complaints. just do something like this: union { const char* constipated; char* freeflow; } constbreaker; and your life will be much happier. now when you need to free up some data that's imprisoned in const-land, do something like this: const char* blorf = "skata"; /* ptr const'ed here */ char* foo; /* but we want to use this */ constbreaker.constipated=blorf; foo=constbreaker.freeflow; Note that C++ won't let you create a union which has any element which has a constructor, so you can't put arbitrary class instances (like string!) in a union. However, the reason you're using this is to work around const and pass a pointer , right? so why would your union ever have anything other than basic data types in it? (or pointers to other fancier C++ish things) ;) happy hacking!
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