reference - Idiomatic way to determine if an object has been destroyed -

i've been trying find better way accomplish determining if particular object has been destroyed (destroy(...)). way i've been doing so:

class c {    bool valid = false;    this(){     valid = true;    }  } 

then do:

c c = new c; c.valid.writeln // true destroy(c); c.valid.writeln // false if(c !is null && !c.valid) c = null; 

i don't see wrong (perhaps can tell me else wrong it) other takes memory , requires putting valid = true; in each constructor (and ugly because uses variable destroyed object). best case, of course, have magical function can tell if object valid or not valid(c); // true / false.

so question if there standard way determine if object has been destroyed (like, gc hasn't collected memory location , valid object sitting in spot without reference vtable) , pointer virtually dangling? if there isn't way secondary question: method dangerous in foreseeable way?

previously, made sure each reference object -> b there reference b -> a, , upon applying destroy a's destructor nullified b's reference a. never had check if destroyed. tedious , time consuming when want add new type of reference because have modify both destroyable class (a) , referencing class (b). theoretically, having determinable cycle in reference graph of program (or that); potentially interesting subject.

sorry in advance if i'm being idiot.

by default d use gc deal reference types (class in case). means if use defaults, can't expect deterministic object destruction.

jonathan explained nicely in thread: usage preference between struct , class in d language

if need deterministic destruction - use structs. method described reminds me of scala's option type.