Object* const_missing(STATE, Symbol* sym, CallFrame* call_frame) {
Module* under;
StaticScope* scope = call_frame->static_scope();
if(scope->nil_p()) {
under = G(object);
} else {
under = scope->module();
}
Array* args = Array::create(state, 1);
args->set(state, 0, sym);
return under->send(state, call_frame, G(sym_const_missing), args);
}
Object* const_get(STATE, CallFrame* call_frame, Symbol* name, bool* found) {
StaticScope *cur;
Object* result;
*found = false;
call_frame = call_frame->top_ruby_frame();
// Ok, this has to be explained or it will be considered black magic.
// The scope chain always ends with an entry at the top that contains
// a parent of nil, and a module of Object. This entry is put in
// regardless of lexical scoping, it's the default scope.
//
// When looking up a constant, we don't want to consider the default
// scope (ie, Object) initially because we need to lookup up
// the superclass chain first, because falling back on the default.
//
// The rub comes from the fact that if a user explicitly opens up
// Object in their code, we DO consider it. Like:
//
// class Idiot
// A = 2
// end
//
// class ::Object
// A = 1
// class Stupid < Idiot
// def foo
// p A
// end
// end
// end
//
// In this code, when A is looked up, Object must be considering during
// the scope walk, NOT during the superclass walk.
//
// So, in this case, foo would print "1", not "2".
//
cur = call_frame->static_scope();
while(!cur->nil_p()) {
// Detect the toplevel scope (the default) and get outta dodge.
if(cur->top_level_p(state)) break;
result = cur->module()->get_const(state, name, found);
if(*found) return result;
cur = cur->parent();
}
// Now look up the superclass chain.
cur = call_frame->static_scope();
if(!cur->nil_p()) {
Module* mod = cur->module();
while(!mod->nil_p()) {
result = mod->get_const(state, name, found);
if(*found) return result;
mod = mod->superclass();
}
}
// Lastly, check Object specifically
result = G(object)->get_const(state, name, found, true);
if(*found) return result;
return Qnil;
}
