+Host* Host::by_name_or_null(const char* name)
+{
+ return (Host*) xbt_dict_get_or_null(host_list, name);
+}
+Host* Host::by_name_or_create(const char* name)
+{
+ Host* host = by_name_or_null(name);
+ if (host == nullptr) {
+ host = new Host(name);
+ xbt_dict_set(host_list, name, host, NULL);
+ }
+ return host;
+}