Example for discussion

counted_ptr<T> ptr(new T());

needs a counter
allocation could fail
so may constructor throw?
and should it delete initialiser?

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Notes:

There are a number of possible ways to implement counted_ptr…

Prevent the constructor throwing exceptions (at the cost of possible exceptions in copy ops - e.g. assignment)

The constructor throws, and the user code is responsible for deleting the T.

Should an exception occur, then the counted_ptr deletes the T.