I'm doing this:
template<typename T> class var_accessor {
public:
std::set<std::shared_ptr<T>> varset;
std::map<std::string,std::shared_ptr<T>> vars_by_name;
std::map<uint32,std::shared_ptr<T>> vars_by_id;
std::shared_ptr<T> operator[](const uint32& index) { return vars_by_id[index]; }
std::shared_ptr<T> operator[](const std::string& index) { return vars_by_name[index]; }
bool is_in_set(std::shared_ptr<T> what) { auto it = varset.find(what); if (it == varset.end()) return false; return true; }
bool is_in_set(uint32 what) { auto it = vars_by_id.find(what); if (it == vars_by_id.end()) return false; return true; }
bool is_in_set(std::string& what) { auto it = vars_by_name.find(what); if (it == vars_by_name.end()) return false; return true; }
bool place(std::shared_ptr<T> what, const uint32 whatid, const std::string& whatstring) {
if (is_in_set(what)) return false;
varset.emplace(what);
vars_by_name.emplace(whatstring,what);
vars_by_id.emplace(whatid,what);
return true;
}
};
Then...
class whatever {
std::string name;
std::function<int32()> exec;
};
And:
class foo {
public:
var_accessor<whatever> stuff;
};
This works:
std::shared_ptr<whatever> thing(new whatever);
thing->name = "Anne";
thing->exec = []() { return 1; }
foo person;
person.stuff.emplace(thing, 1, thing->name);
Getting the name crashes it:
std::cout << person.stuff[1]->name;
But if I change the operator[]'s to return references, it works fine.
I don't want to be able to accidentally add new elements without adding to all 3 structures, so that's why I made
std::shared_ptr<T> operator[]
instead of
std::shared_ptr<T>& operator[]
Is there any way to prevent assignment by subscript but keep the subscript operator working?
To be clear I want to be able to keep doing
std::cout << person.stuff[4];
But NOT be able to do
std::shared_ptr<whatever> bob(new whatever);
bob->name = "bob";
person.stuff[2] = bob;
The error is a EXC_BAD_ACCESS inside the std::string class madness Everything I read says simply "don't return references if you want to prevent assignment" but it also prevents using it for me.
Yes I know some things should be made private but I just want to get it working first.
Using Clang/LLVM in XCode 5.1 Thanks!
