ConnectorFactory

ConnectorFactory is a singleton registry that maps connector type strings to factory functions returning std::shared_ptr<ExchangeConnector>.

class ConnectorFactory {
public:
  using CreatorFunc =
      std::move_only_function<std::shared_ptr<ExchangeConnector>(const std::string& symbol)>;

  static ConnectorFactory& instance();                        // global access

  void registerConnector(const std::string& type,
                         CreatorFunc creator);                // add mapping

  std::optional<std::shared_ptr<ExchangeConnector>>
  createConnector(const std::string& type,
                  const std::string& symbol);                 // get new connector

private:
  ConnectorFactory() = default;
  std::unordered_map<std::string, CreatorFunc> _creators;     // type → factory
};

Purpose

• Decouple engine configuration from concrete ExchangeConnector classes.
• Enable dynamic creation of connectors (Bybit, Binance, Mock, …) via config strings.

Responsibilities

Action	Behaviour
registerConnector	Stores a move-only CreatorFunc under its type key.
createConnector	Looks up the type; if found, returns a new instance for the given symbol.
Singleton lifetime	instance() guarantees one global registry for the entire process.

Internal Behaviour

• _creators is an unordered_map<std::string, CreatorFunc>; look-ups are O(1) average.
• CreatorFunc is std::move_only_function, ensuring no accidental copies of heavy lambdas / bindings.
• If a type is missing, createConnector returns std::nullopt so callers can handle errors gracefully.

Usage Example

// registration (usually in connector module init)
ConnectorFactory::instance().registerConnector(
    "bybit",
    [](const std::string& sym) {
      return std::make_shared<BybitExchangeConnector>(sym);
    });

// creation (engine startup)
auto connOpt = ConnectorFactory::instance().createConnector("bybit", "DOTUSDT");
if (connOpt) engine.addConnector(*connOpt);

Notes

• Thread safety: registration is typically done at startup; concurrent reads are fine after that.
• Factory lambdas can capture config (API keys, WS endpoints) before registration.