Crow::run()会调用Crow::validate()，而后者会调用router_.validate();

void validate()
{//Take all the routes from the registered blueprints and add them to `all_rules_` to be processed.detail::middleware_indices blueprint_mw;validate_bp(blueprints_, blueprint_mw);for (auto& rule : all_rules_){if (rule){auto upgraded = rule->upgrade();if (upgraded)rule = std::move(upgraded);rule->validate();internal_add_rule_object(rule->rule(), rule.get(), INVALID_BP_ID, blueprints_);}}for (auto& per_method : per_methods_){per_method.trie.validate();}
}

1.Crow：黑魔法 添加路由3 绑定lambda-CSDN博客

  解释了