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Boost Users : |
Subject: [Boost-users] [ptr_container][ptr_map]
From: Aaron Levy (aaron.levy_at_[hidden])
Date: 2014-09-13 16:52:43
Consider the following code:
class Base
{
public:
virtual ~Base() = 0 {};
virtual double get() = 0;
};
class D1 : public Base
{
public:
D1(double n) : val_(n) {}
double get() const { return val_; }
private:
double val_;
};
class D2 : public Base
{
D2(double n) : val_(n) {}
double get() const { return val_; }
private:
double val_;
};
bool operator < (const Base& left, const Base& right)
{
return (left.get() < right.get());
}
I can create a ptr_set of Base like this:
boost::ptr_set<Base> set;
But I can't create a ptr_map with Base as key, like this:
boost::ptr_map<Base, Base> map;
The problem is that Base is abstract and so the key cannot be instantiated by ptr_map. What is the cause for this distinction between ptr_set and ptr_map.
-- Aaron Levy aaron.levy_at_[hidden]
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