c++ - Design pattern for accessing non-const through a const intermediate -

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can suggest better design situation want 2 objects "talk" each other through const intermediate.

here contrived example, 2 players trade lemons. player finds player in "world", "world" should const, since player shouldn't able modify (lets deleting walls).

void player::give_lemon() {     const world& world = this->get_world();      const player& other = world.get_nearest_player(*this);      this->lemons--;     other.lemons++; // error }

what designs people use, simple const_cast easy dirty. or provide way of "looking up" non-const player reference, lets having access non-const player_list() here we'd duplicating functionality available in world, possibly less efficiently, round-about way of doing specific const_cast.

it seems both player , world can seen actors

world happens const

introduce manager class handles both:

manager take const world in constructor , players can added or removed.

void player::give_lemon() {     manager& mgr = this->get_manager();      player& other = mgr.get_nearest_player(*this);      this->lemons--;     other.lemons++; // error }

the manager keeps track of positions of players in world. world const , cannot have mutable list of players, manager can.


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