Encapsulate std::map to allow iterating, but no di

问题:

This question already has answers here:

Prevent direct access to std::map keys (2 answers)

Closed 2 years ago.

Is there a way to encapsulate std::map within a user-defined class, allowing iteration, but not allowing direct access to the key?

I would like to manipulate the key upon insertion and I want to force all access to elements through a user-defined method (as the key will need to be modified).

I think the problem is allowing iterating over the map, whilst preventing the user from accessing the key via the iterator.

回答1:

Do not expose iterators. Expose a for_each function that passes each element to the user-provided (lambda) function.

Alternatively, use a transform iterator.