digitalmars.D - Function pointers as values?
I was playing with D's function pointers and immutability and ran into some trouble. It's probably because function pointers are treated just like data pointers when it comes to immutability. To mend this, function pointers should be treated as values. It may sound odd but makes sense -- you can't possibly dereference a function pointer, so we're dealing only with addresses themselves and these are values. One of the results of the amendment would be allowing implicit conversion from immutable/const to mutable and vice versa. Note that immutable(void function()) ifp; void function() fp = ifp; // Error: cannot implicitly convert expression (fp) of type immutable(void function()) to void function() is exactly the same as immutable int ii; int i = ii; so should compile. I was also thinking that an expression taking a function's address (&fun) should be an immutable function pointer. Not sure about this one, though. BTW, a quick bugzilla search shows that I'm not the only one who wants function pointers as values. http://d.puremagic.com/issues/show_bug.cgi?id=3650 Tomek
Jan 18 2010