problem in storing objects in Map class

[jeet232]

i have a class 'Root' from which i derived all other classes.

in one of derived class (HashMap), i'm using Map object to store Root objects, making it a very generic class to store any derived class object.

like:
--------
typedef map<Root, Root> Map;
Map data;

put(Root& key, Root& value)
{
data.insert(pair<Root, Root>(key, value));
}


but in the insert line, i'm getting following error:
error: no match for ‘operator<’ in ‘__x < __y’
Root.cpp:43: note: candidates are: bool Root::operator<(Root&)

i've defined: bool operator < (Root&) in Root class, along with == overload.


Please help

[weaknessforcats]

The Root::operator< won't cut it.

You need an operator< that has two const arguments:

bool operator<(const Root& lhs, const Root& rhs)
{
    //etc...
}
 

Also, map of Root objects won't work for derived classes. All that will be in the map is the Root portion of your derived object. The rest will be neatly sliced off.

I suggest a map of Root handles. Read this.