c++ - 带有工厂设计尝试的段错误 unique_ptr

Question

我在尝试使用 unique_ptr 创建派生类的实例时遇到了段错误。之前，我对七个派生类的每个实例都进行了编码，一个接一个，代码运行正常。

当前代码如下:

typedef std::unique_ptr<Comum> ComumPtr;

ComumPtr createInstance ( string dom, map<string, string> & config, map<string, string> & config_fields )
{
    ComumPtr ptr;       // initialized to nullptr.
    if ( dom == "voice" ) {
    ptr.reset ( new Voice (config, config_fields) );
    //    } else if ( dom == "account" ) {     // FOR OTHER DERIVED CLASSES
    //  ptr.reset ( new Account (config, config_fields) );
    }
    return ptr;
}

// At  main function:
 for (vector<string>::const_iterator cit = for_domain.begin(); cit != for_domain.end(); ++cit) { 
    const char * section (cit->c_str());
    string fsn = *cit + "_fields";
    const char * fields_section_name (fsn.c_str());
    const char * db_section ("Database");

    map <string, string> domain_config = cfg.getSectionConfig (config_file.c_str(), section);
    map <string, string> domain_config_fields  = cfg.getSectionConfig (config_file.c_str(), fields_section_name);
    map <string, string> database_config = cfg.getSectionConfig (config_file.c_str(), db_section);

    std::unique_ptr<Comum> domain = createInstance(*cit, domain_config, domain_config_fields);

    domain->readDatabaseFields (database_config);   // <- segmentation fault

您认为这会导致段错误吗？

Answer 1

函数createInstance有机会返回nullptr，需要检查指针是否有效:

if (domain.get())
{
  domain->readDatabaseFields (database_config);
}