X-Git-Url: http://info.iut-bm.univ-fcomte.fr/pub/gitweb/simgrid.git/blobdiff_plain/3c22fdea313dc38d430071450a15015f0746632b..9c134fb43e3965db16815a46839ab063e2b05282:/src/xbt/config.cpp

diff --git a/src/xbt/config.cpp b/src/xbt/config.cpp
index 7c8619f8a3..45c09e8b05 100644
--- a/src/xbt/config.cpp
+++ b/src/xbt/config.cpp
@@ -3,7 +3,11 @@
 
 #include <stdio.h>
 
+#include <cerrno>
+#include <cstring>
+#include <climits>
 #include <functional>
+#include <stdexcept>
 #include <string>
 #include <type_traits>
 
@@ -22,9 +26,21 @@ XBT_LOG_NEW_DEFAULT_SUBCATEGORY(xbt_cfg, xbt, "configuration support");
 
 XBT_EXPORT_NO_IMPORT(xbt_cfg_t) simgrid_config = NULL;
 
+/** @brief possible content of each configuration cell */
+typedef enum {
+  xbt_cfgelm_int = 0,                    /**< int */
+  xbt_cfgelm_double,                     /**< double */
+  xbt_cfgelm_string,                    /**< char* */
+  xbt_cfgelm_boolean,                   /**< int */
+  //! @cond
+  xbt_cfgelm_any,               /* not shown to users to prevent errors */
+  xbt_cfgelm_type_count
+  //! @endcond
+} e_xbt_cfgelm_type_t;
+
+
 namespace {
 
-// We could define some range/iterator for the num values.
 static inline
 void increment(e_xbt_cfgelm_type_t& type)
 {
@@ -34,116 +50,186 @@ void increment(e_xbt_cfgelm_type_t& type)
 
 }
 
-/* xbt_cfgelm_t: the typedef corresponding to a config variable. */
+static const char *xbt_cfgelm_type_name[xbt_cfgelm_type_count] = {
+  "int", "double", "string", "boolean", "any"
+};
+
+/** Boolean possible values **/
+struct xbt_boolean_couple {
+  const char *true_val;
+  const char *false_val;
+};
+
+const struct xbt_boolean_couple xbt_cfgelm_boolean_values[] = {
+  { "yes",    "no"},
+  {  "on",   "off"},
+  {"true", "false"},
+  {   "1",     "0"},
+  {  NULL,    NULL}
+};
+
+namespace simgrid {
+namespace config {
+  struct ConfigurationElement ;
+  class Config;
+}
+}
+
+/* Retrieve the variable we'll modify */
+static simgrid::config::ConfigurationElement* xbt_cfgelm_get(xbt_cfg_t cfg, const char *name, e_xbt_cfgelm_type_t type);
 
-typedef struct {
+namespace simgrid {
+namespace config {
+
+// A configuration variable:
+struct ConfigurationElement {
   /* Description */
-  char *desc;
+  std::string desc;
 
   /* Allowed type of the variable */
   e_xbt_cfgelm_type_t type;
-  unsigned isdefault:1;
+  bool isdefault = true;
 
-  /* Callbacks */
-  xbt_cfg_cb_t cb_set;
+  /* Callback */
+  xbt_cfg_cb_t cb_set = nullptr;
 
-  /* Advanced callbacks */
-  xbt_cfg_cb_ext_t cb_set_ext;
-  void* cb_set_data;
-  xbt_cfg_cb_free_t cb_set_free;
+  /* Advanced callback (for xbt_cfgelm_string only) */
+  std::function<void(const char* value)> callback;
 
-  /* actual content (could be an union or something) */
-  xbt_dynar_t content;
-} s_xbt_cfgelm_t, *xbt_cfgelm_t;
+  union {
+    int int_content;
+    double double_content;
+    char* string_content;
+    bool boolean_content;
+  };
 
-static const char *xbt_cfgelm_type_name[xbt_cfgelm_type_count] = { "int", "double", "string", "boolean", "any", "outofbound" };
+  ~ConfigurationElement()
+  {
+    XBT_DEBUG("Frees cfgelm %p", this);
+    switch(this->type) {
+    case xbt_cfgelm_int:
+    case xbt_cfgelm_double:
+    case xbt_cfgelm_boolean:
+      break;
+    case xbt_cfgelm_string:
+      free(string_content);
+      break;
+    default:
+      xbt_die("Unexpected config type");
+    }
+  }
 
-const struct xbt_boolean_couple xbt_cfgelm_boolean_values[] = {
-  { "yes",    "no"},
-  {  "on",   "off"},
-  {"true", "false"},
-  {   "1",     "0"},
-  {  NULL,    NULL}
+};
+
+class Config {
+  // name -> ConfigElement:
+  xbt_dict_t options;
+  // alias -> xbt_dict_elm_t from options:
+  xbt_dict_t aliases;
+
+public:
+  Config();
+  ~Config();
+
+  // No copy:
+  Config(Config const&) = delete;
+  Config& operator=(Config const&) = delete;
+
+  xbt_dictelm_t getElement(const char* name);
+  ConfigurationElement* operator[](const char* name);
+  void alias(const char* realname, const char* aliasname);
+
+  simgrid::config::ConfigurationElement* registerOption(
+    const char *name, const char *desc, e_xbt_cfgelm_type_t type,
+    xbt_cfg_cb_t cb_set);
+
+  // Debug:
+  void dump(const char *name, const char *indent);
+  void showAliases();
+  void help();
 };
 
 /* Internal stuff used in cache to free a variable */
-static void xbt_cfgelm_free(void *data);
+static void xbt_cfgelm_free(void *data)
+{
+  if (data)
+    delete (simgrid::config::ConfigurationElement*) data;
+}
 
-/* Retrieve the variable we'll modify */
-static xbt_cfgelm_t xbt_cfgelm_get(xbt_cfg_t cfg, const char *name, e_xbt_cfgelm_type_t type);
+Config::Config() :
+  options(xbt_dict_new_homogeneous(xbt_cfgelm_free)),
+  aliases(xbt_dict_new_homogeneous(NULL))
+{}
 
-/*----[ Memory management ]-----------------------------------------------*/
-/** @brief Constructor
- *
- * Initialise a config set
- */
-xbt_cfg_t xbt_cfg_new(void)
+Config::~Config()
 {
-  return (xbt_cfg_t) xbt_dict_new_homogeneous(&xbt_cfgelm_free);
+  XBT_DEBUG("Frees cfg set %p", this);
+  xbt_dict_free(&this->options);
+  xbt_dict_free(&this->aliases);
 }
 
-/** @brief Destructor */
-void xbt_cfg_free(xbt_cfg_t * cfg)
+inline
+xbt_dictelm_t Config::getElement(const char* name)
+{
+  // We are interested in the options dictelm:
+  xbt_dictelm_t res = xbt_dict_get_elm_or_null(options, name);
+  if (res)
+    return res;
+  // The aliases dict stores pointers to the options dictelm:
+  res = (xbt_dictelm_t) xbt_dict_get_or_null(aliases, name);
+  if (res)
+    XBT_INFO("Option %s has been renamed to %s. Consider switching.", name, res->key);
+  return res;
+}
+
+inline
+ConfigurationElement* Config::operator[](const char* name)
+{
+  xbt_dictelm_t elm = getElement(name);
+  if (elm)
+    return (ConfigurationElement*) elm->content;
+  else
+    return nullptr;
+}
+
+void Config::alias(const char* realname, const char* aliasname)
 {
-  XBT_DEBUG("Frees cfg set %p", cfg);
-  xbt_dict_free((xbt_dict_t *) cfg);
+  xbt_assert(this->getElement(aliasname) == nullptr, "Alias '%s' already.", aliasname);
+  xbt_dictelm_t element = this->getElement(realname);
+  xbt_assert(element, "Cannot define an alias to the non-existing option '%s'.", realname);
+  xbt_dict_set(this->aliases, aliasname, element, NULL);
 }
 
 /** @brief Dump a config set for debuging purpose
  *
  * @param name The name to give to this config set
  * @param indent what to write at the beginning of each line (right number of spaces)
- * @param cfg the config set
  */
-void xbt_cfg_dump(const char *name, const char *indent, xbt_cfg_t cfg)
+void Config::dump(const char *name, const char *indent)
 {
-  xbt_dict_t dict = (xbt_dict_t) cfg;
+  xbt_dict_t dict = this->options;
   xbt_dict_cursor_t cursor = NULL;
-  xbt_cfgelm_t variable = NULL;
+  simgrid::config::ConfigurationElement* variable = NULL;
   char *key = NULL;
-  int i;
-  int size;
-  int ival;
-  char *sval;
-  double dval;
 
   if (name)
     printf("%s>> Dumping of the config set '%s':\n", indent, name);
 
   xbt_dict_foreach(dict, cursor, key, variable) {
-    printf("%s  %s:", indent, key);
-
-    size = xbt_dynar_length(variable->content);
-    printf ("%s. Actual size=%d. postset=%p\n",
-            xbt_cfgelm_type_name[variable->type], size, variable->cb_set);
-
+    const char* type_name = xbt_cfgelm_type_name[variable->type];
     switch (variable->type) {
     case xbt_cfgelm_int:
-      for (i = 0; i < size; i++) {
-        ival = xbt_dynar_get_as(variable->content, i, int);
-        printf("%s    %d\n", indent, ival);
-      }
+      printf("%s  %s: ()%s) %i", indent, key, type_name, variable->int_content);
       break;
     case xbt_cfgelm_double:
-      for (i = 0; i < size; i++) {
-        dval = xbt_dynar_get_as(variable->content, i, double);
-        printf("%s    %f\n", indent, dval);
-      }
+      printf("%s  %s: ()%s) %f", indent, key, type_name, variable->double_content);
       break;
     case xbt_cfgelm_string:
-      for (i = 0; i < size; i++) {
-        sval = xbt_dynar_get_as(variable->content, i, char *);
-        printf("%s    %s\n", indent, sval);
-      }
+      printf("%s  %s: ()%s) %s", indent, key, type_name, variable->string_content);
       break;
     case xbt_cfgelm_boolean:
-      for (i = 0; i < size; i++) {
-        ival = xbt_dynar_get_as(variable->content, i, int);
-        printf("%s    %d\n", indent, ival);
-      }
-      break;
-    case xbt_cfgelm_alias:
-      /* no content */
+      printf("%s  %s: ()%s) %s", indent, key, type_name,
+        variable->boolean_content ? "true" : "false");
       break;
     default:
       printf("%s    Invalid type!!\n", indent);
@@ -158,354 +244,223 @@ void xbt_cfg_dump(const char *name, const char *indent, xbt_cfg_t cfg)
   xbt_dict_cursor_free(&cursor);
 }
 
-/*
- * free an config element
- */
-void xbt_cfgelm_free(void *data)
+simgrid::config::ConfigurationElement* Config::registerOption(
+  const char *name, const char *desc, e_xbt_cfgelm_type_t type, xbt_cfg_cb_t cb_set)
 {
-  xbt_cfgelm_t c = (xbt_cfgelm_t) data;
-
-  XBT_DEBUG("Frees cfgelm %p", c);
-  if (!c)
-    return;
-  if (c->cb_set_free)
-    c->cb_set_free(c->cb_set_data);
-  xbt_free(c->desc);
-  if (c->type != xbt_cfgelm_alias)
-    xbt_dynar_free(&(c->content));
-  free(c);
-}
-
-/*----[ Registering stuff ]-----------------------------------------------*/
-/** @brief Register an element within a config set
- *
- *  @param cfg the config set
- *  @param name the name of the config element
- *  @param desc a description for this item (used by xbt_cfg_help())
- *  @param type the type of the config element
- *  @param cb_set callback function called when a value is set
- */
-static void xbt_cfg_register(
-  xbt_cfg_t * cfg, const char *name, const char *desc, e_xbt_cfgelm_type_t type,
-  xbt_cfg_cb_t cb_set,
-  xbt_cfg_cb_ext_t cb_set_ext, void* cb_set_data, xbt_cfg_cb_free_t cb_set_free)
-{
-  if (*cfg == NULL)
-    *cfg = xbt_cfg_new();
   xbt_assert(type >= xbt_cfgelm_int && type <= xbt_cfgelm_boolean,
               "type of %s not valid (%d should be between %d and %d)",
              name, (int)type, xbt_cfgelm_int, xbt_cfgelm_boolean);
 
-  xbt_cfgelm_t res = (xbt_cfgelm_t) xbt_dict_get_or_null((xbt_dict_t) * cfg, name);
+  simgrid::config::ConfigurationElement* res = (simgrid::config::ConfigurationElement*) xbt_dict_get_or_null(this->options, name);
   xbt_assert(NULL == res, "Refusing to register the config element '%s' twice.", name);
 
-  res = xbt_new(s_xbt_cfgelm_t, 1);
+  res = new simgrid::config::ConfigurationElement();
   XBT_DEBUG("Register cfg elm %s (%s) (%s (=%d) @%p in set %p)",
-            name, desc, xbt_cfgelm_type_name[type], (int)type, res, *cfg);
-
-  res->desc = xbt_strdup(desc);
+            name, desc, xbt_cfgelm_type_name[type], (int)type, res, this);
   res->type = type;
   res->cb_set = cb_set;
-  res->cb_set_ext = cb_set_ext;
-  res->cb_set_data = cb_set_data;
-  res->cb_set_free = cb_set_free;
-  res->isdefault = 1;
+  if (desc)
+    res->desc = desc;
 
+  // Set a default default value:
   switch (type) {
   case xbt_cfgelm_int:
-    res->content = xbt_dynar_new(sizeof(int), NULL);
+    res->int_content = 0;
     break;
   case xbt_cfgelm_double:
-    res->content = xbt_dynar_new(sizeof(double), NULL);
+    res->double_content = 0.0;
     break;
   case xbt_cfgelm_string:
-    res->content = xbt_dynar_new(sizeof(char *), xbt_free_ref);
+    res->string_content = nullptr;
     break;
   case xbt_cfgelm_boolean:
-    res->content = xbt_dynar_new(sizeof(int), NULL);
+    res->boolean_content = false;
     break;
   default:
     XBT_ERROR("%d is an invalid type code", (int)type);
     break;
   }
-  xbt_dict_set((xbt_dict_t) * cfg, name, res, NULL);
-}
-
-
-
-void xbt_cfg_register_double(const char *name, double default_value,xbt_cfg_cb_t cb_set, const char *desc){
-  xbt_cfg_register(&simgrid_config,name,desc,xbt_cfgelm_double,cb_set, NULL, NULL, NULL);
-  xbt_cfg_setdefault_double(name, default_value);
-}
-void xbt_cfg_register_int(const char *name, int default_value,xbt_cfg_cb_t cb_set, const char *desc) {
-  xbt_cfg_register(&simgrid_config,name,desc,xbt_cfgelm_int,cb_set, NULL, NULL, NULL);
-  xbt_cfg_setdefault_int(name, default_value);
-}
-void xbt_cfg_register_string(const char *name, const char *default_value, xbt_cfg_cb_t cb_set, const char *desc){
-  xbt_cfg_register(&simgrid_config,name,desc,xbt_cfgelm_string,cb_set, NULL, NULL, NULL);
-  xbt_cfg_setdefault_string(name, default_value);
-}
-void xbt_cfg_register_boolean(const char *name, const char*default_value,xbt_cfg_cb_t cb_set, const char *desc){
-  xbt_cfg_register(&simgrid_config,name,desc,xbt_cfgelm_boolean,cb_set, NULL, NULL, NULL);
-  xbt_cfg_setdefault_boolean(name, default_value);
-}
-
-/** Register a config with an extended callback
- *
- *  @param name      Name of the flag
- *  @param desc      Description of the flag
- *  @param type      Type of the flag
- *  @param cb        Extended callback
- *  @param data      Data associated with the callback
- *  @param data_free Function used to free the callback data (or NULL)
- */
-void xbt_cfg_register_ext(const char *name, const char *desc, e_xbt_cfgelm_type_t type,
-  xbt_cfg_cb_ext_t cb, void* data, xbt_cfg_cb_free_t data_free)
-{
-  xbt_cfg_register(&simgrid_config, name, desc, type, NULL, cb, data, data_free);
-}
-
-void xbt_cfg_register_alias(const char *newname, const char *oldname)
-{
-  if (simgrid_config == NULL)
-    simgrid_config = xbt_cfg_new();
-
-  xbt_cfgelm_t res = (xbt_cfgelm_t) xbt_dict_get_or_null((xbt_dict_t) simgrid_config, oldname);
-  xbt_assert(NULL == res, "Refusing to register the option '%s' twice.", oldname);
-
-  res = (xbt_cfgelm_t) xbt_dict_get_or_null((xbt_dict_t) simgrid_config, newname);
-  xbt_assert(res, "Cannot define an alias to the non-existing option '%s'.", newname);
-
-  res = xbt_new0(s_xbt_cfgelm_t, 1);
-  XBT_DEBUG("Register cfg alias %s -> %s)",oldname,newname);
-
-  res->desc = bprintf("Deprecated alias for %s",newname);
-  res->type = xbt_cfgelm_alias;
-  res->isdefault = 1;
-  res->content = (xbt_dynar_t)newname;
-
-  xbt_dict_set((xbt_dict_t) simgrid_config, oldname, res, NULL);
-}
 
-/**
- * @brief Parse a string and register the stuff described.
- *
- * @param cfg the config set
- * @param entry a string describing the element to register
- *
- * The string may consist in several variable descriptions separated by a space.
- * Each of them must use the following syntax: \<name\>:\<type\>
- * with type being one of  'string','int','bool' or 'double'.
- *
- * Note that this does not allow to set the description, so you should prefer the other interface
- */
-void xbt_cfg_register_str(xbt_cfg_t * cfg, const char *entry)
-{
-  char *entrycpy = xbt_strdup(entry);
-  char *tok;
-
-  e_xbt_cfgelm_type_t type;
-  XBT_DEBUG("Register string '%s'", entry);
-
-  tok = strchr(entrycpy, ':');
-  xbt_assert(tok, "Invalid config element descriptor: %s; Should be <name>:<type>", entry);
-  *(tok++) = '\0';
-
-  for (type = (e_xbt_cfgelm_type_t)0; type < xbt_cfgelm_type_count && strcmp(tok, xbt_cfgelm_type_name[type]); increment(type));
-  xbt_assert(type < xbt_cfgelm_type_count,
-      "Invalid type in config element descriptor: %s; Should be one of 'string', 'int' or 'double'.", entry);
-
-  xbt_cfg_register(cfg, entrycpy, NULL, type, NULL, NULL, NULL, NULL);
-
-  free(entrycpy);               /* strdup'ed by dict mechanism, but cannot be const */
+  xbt_dict_set(this->options, name, res, NULL);
+  return res;
 }
 
 /** @brief Displays the declared aliases and their description */
-void xbt_cfg_aliases(void)
+void Config::showAliases()
 {
   xbt_dict_cursor_t dict_cursor;
   unsigned int dynar_cursor;
-  xbt_cfgelm_t variable;
+  xbt_dictelm_t dictel;
   char *name;
   xbt_dynar_t names = xbt_dynar_new(sizeof(char *), NULL);
 
-  xbt_dict_foreach((xbt_dict_t )simgrid_config, dict_cursor, name, variable)
+  xbt_dict_foreach(this->aliases, dict_cursor, name, dictel)
     xbt_dynar_push(names, &name);
   xbt_dynar_sort_strings(names);
 
   xbt_dynar_foreach(names, dynar_cursor, name) {
-    variable = (xbt_cfgelm_t) xbt_dict_get((xbt_dict_t )simgrid_config, name);
-
-    if (variable->type == xbt_cfgelm_alias)
-      printf("   %s: %s\n", name, variable->desc);
+    simgrid::config::ConfigurationElement* variable = (*this)[name];
+    if (variable)
+      printf("   %s: %s\n", name, variable->desc.c_str());
   }
 }
 
 /** @brief Displays the declared options and their description */
-void xbt_cfg_help(void)
+void Config::help()
 {
   xbt_dict_cursor_t dict_cursor;
   unsigned int dynar_cursor;
-  xbt_cfgelm_t variable;
+  simgrid::config::ConfigurationElement* variable;
   char *name;
   xbt_dynar_t names = xbt_dynar_new(sizeof(char *), NULL);
 
-  xbt_dict_foreach((xbt_dict_t )simgrid_config, dict_cursor, name, variable)
+  xbt_dict_foreach(this->options, dict_cursor, name, variable)
     xbt_dynar_push(names, &name);
   xbt_dynar_sort_strings(names);
 
   xbt_dynar_foreach(names, dynar_cursor, name) {
-    int size;
-    variable = (xbt_cfgelm_t) xbt_dict_get((xbt_dict_t )simgrid_config, name);
-    if (variable->type == xbt_cfgelm_alias)
-      continue;
+    variable = (simgrid::config::ConfigurationElement*) xbt_dict_get(this->options, name);
 
-    printf("   %s: %s\n", name, variable->desc);
+    printf("   %s: %s\n", name, variable->desc.c_str());
     printf("       Type: %s; ", xbt_cfgelm_type_name[variable->type]);
-    size = xbt_dynar_length(variable->content);
     printf("Current value: ");
 
-    if (size != 1)
-      printf(size == 0 ? "n/a\n" : "{ ");
-    for (int i = 0; i < size; i++) {
-      const char *sep = (size == 1 ? "\n" : (i < size - 1 ? ", " : " }\n"));
-
       switch (variable->type) {
       case xbt_cfgelm_int:
-        printf("%d%s", xbt_dynar_get_as(variable->content, i, int), sep);
+        printf("%d\n", variable->int_content);
         break;
       case xbt_cfgelm_double:
-        printf("%f%s", xbt_dynar_get_as(variable->content, i, double), sep);
+        printf("%f\n", variable->double_content);
         break;
       case xbt_cfgelm_string:
-        printf("'%s'%s", xbt_dynar_get_as(variable->content, i, char *), sep);
+        printf("'%s'\n", variable->string_content);
         break;
-      case xbt_cfgelm_boolean: {
-        int b = xbt_dynar_get_as(variable->content, i, int);
-        const char *bs = b ? xbt_cfgelm_boolean_values[0].true_val: xbt_cfgelm_boolean_values[0].false_val;
-        if (b == 0 || b == 1)
-          printf("'%s'%s", bs, sep);
-        else
-          printf("'%s/%d'%s", bs, b, sep);
+      case xbt_cfgelm_boolean:
+        printf("'%s'\n", variable->boolean_content ? "true" : "false");
         break;
-      }
       default:
-        printf("Invalid type!!%s", sep);
+        printf("Invalid type!!\n");
         break;
       }
-    }
+
   }
   xbt_dynar_free(&names);
 }
 
-static xbt_cfgelm_t xbt_cfgelm_get(xbt_cfg_t cfg, const char *name, e_xbt_cfgelm_type_t type)
-{
-  xbt_cfgelm_t res = (xbt_cfgelm_t) xbt_dict_get_or_null((xbt_dict_t) cfg, name);
+}
+}
 
-  // The user used the old name. Switch to the new one after a short warning
-  while (res && res->type == xbt_cfgelm_alias) {
-    const char* newname = (const char *)res->content;
-    XBT_INFO("Option %s has been renamed to %s. Consider switching.", name, newname);
-    res = xbt_cfgelm_get(cfg, newname, type);
-  }
+// C bindings:
 
-  if (!res) {
-    xbt_cfg_help();
-    fflush(stdout);
-    THROWF(not_found_error, 0, "No registered variable '%s' in this config set.", name);
-  }
+/** @brief Constructor */
+xbt_cfg_t xbt_cfg_new(void)        { return new simgrid::config::Config(); }
+/** @brief Destructor */
+void xbt_cfg_free(xbt_cfg_t * cfg) { delete *cfg; }
 
-  xbt_assert(type == xbt_cfgelm_any || res->type == type,
-              "You tried to access to the config element %s as an %s, but its type is %s.",
-              name, xbt_cfgelm_type_name[type], xbt_cfgelm_type_name[res->type]);
-  return res;
+void xbt_cfg_dump(const char *name, const char *indent, xbt_cfg_t cfg)
+{
+  cfg->dump(name, indent);
 }
 
-/** @brief Get the type of this variable in that configuration set
- *
- * @param cfg the config set
- * @param name the name of the element
+/*----[ Registering stuff ]-----------------------------------------------*/
+/** @brief Register an element within a config set
  *
- * @return the type of the given element
+ *  @param cfg the config set
+ *  @param name the name of the config element
+ *  @param desc a description for this item (used by xbt_cfg_help())
+ *  @param type the type of the config element
+ *  @param cb_set callback function called when a value is set
  */
-e_xbt_cfgelm_type_t xbt_cfg_get_type(xbt_cfg_t cfg, const char *name)
+static simgrid::config::ConfigurationElement* xbt_cfg_register(
+  xbt_cfg_t * cfg, const char *name, const char *desc, e_xbt_cfgelm_type_t type, xbt_cfg_cb_t cb_set)
 {
-  xbt_cfgelm_t variable = NULL;
+  if (*cfg == NULL)
+    *cfg = xbt_cfg_new();
+  return (*cfg)->registerOption(name, desc, type, cb_set);
+}
 
-  variable = (xbt_cfgelm_t) xbt_dict_get_or_null((xbt_dict_t) cfg, name);
-  if (!variable)
-    THROWF(not_found_error, 0, "Can't get the type of '%s' since this variable does not exist", name);
+void xbt_cfg_register_double(const char *name, double default_value,xbt_cfg_cb_t cb_set, const char *desc)
+{
+  xbt_cfg_register(&simgrid_config, name, desc, xbt_cfgelm_double, cb_set);
+  xbt_cfg_setdefault_double(name, default_value);
+}
+void xbt_cfg_register_int(const char *name, int default_value,xbt_cfg_cb_t cb_set, const char *desc)
+{
+  xbt_cfg_register(&simgrid_config, name, desc, xbt_cfgelm_int, cb_set);
+  xbt_cfg_setdefault_int(name, default_value);
+}
+void xbt_cfg_register_string(const char *name, const char *default_value, xbt_cfg_cb_t cb_set, const char *desc)
+{
+  xbt_cfg_register(&simgrid_config,name,desc,xbt_cfgelm_string,cb_set);
+  xbt_cfg_setdefault_string(name, default_value);
+}
+void xbt_cfg_register_boolean(const char *name, const char*default_value,xbt_cfg_cb_t cb_set, const char *desc)
+{
+  xbt_cfg_register(&simgrid_config,name,desc,xbt_cfgelm_boolean,cb_set);
+  xbt_cfg_setdefault_boolean(name, default_value);
+}
 
-  XBT_DEBUG("type in variable = %d", (int)variable->type);
-  return variable->type;
+void xbt_cfg_register_alias(const char *realname, const char *aliasname)
+{
+  if (simgrid_config == NULL)
+    simgrid_config = xbt_cfg_new();
+  simgrid_config->alias(realname, aliasname);
 }
 
-/*----[ Setting ]---------------------------------------------------------*/
-/**  @brief va_args version of xbt_cfg_set
+/**
+ * @brief Parse a string and register the stuff described.
  *
- * @param cfg config set to fill
- * @param name  variable name
- * @param pa  variable value
+ * @param cfg the config set
+ * @param entry a string describing the element to register
  *
- * Add some values to the config set.
+ * The string may consist in several variable descriptions separated by a space.
+ * Each of them must use the following syntax: \<name\>:\<type\>
+ * with type being one of  'string','int','bool' or 'double'.
+ *
+ * Note that this does not allow to set the description, so you should prefer the other interface
  */
-void xbt_cfg_set_vargs(xbt_cfg_t cfg, const char *name, va_list pa)
+void xbt_cfg_register_str(xbt_cfg_t * cfg, const char *entry)
 {
-  char *str;
-  int i;
-  double d;
-  e_xbt_cfgelm_type_t type = xbt_cfgelm_type_count; /* Set a dummy value to make gcc happy. It cannot get uninitialized */
+  char *entrycpy = xbt_strdup(entry);
+  char *tok;
 
-  xbt_ex_t e;
+  e_xbt_cfgelm_type_t type;
+  XBT_DEBUG("Register string '%s'", entry);
 
-  TRY {
-    type = xbt_cfg_get_type(cfg, name);
-  }
-  CATCH(e) {
-    if (e.category == not_found_error) {
-      xbt_ex_free(e);
-      THROWF(not_found_error, 0, "Can't set the property '%s' since it's not registered", name);
-    }
-    RETHROW;
-  }
+  tok = strchr(entrycpy, ':');
+  xbt_assert(tok, "Invalid config element descriptor: %s; Should be <name>:<type>", entry);
+  *(tok++) = '\0';
 
-  switch (type) {
-  case xbt_cfgelm_string:
-    str = va_arg(pa, char *);
-    xbt_cfg_set_string(name, str);
-    break;
-  case xbt_cfgelm_int:
-    i = va_arg(pa, int);
-    xbt_cfg_set_int(name, i);
-    break;
-  case xbt_cfgelm_double:
-    d = va_arg(pa, double);
-    xbt_cfg_set_double(name, d);
-    break;
-  case xbt_cfgelm_boolean:
-    str = va_arg(pa, char *);
-    xbt_cfg_set_boolean(name, str);
-    break;
-  default:
-    xbt_die("Config element variable %s not valid (type=%d)", name, (int)type);
-  }
+  for (type = (e_xbt_cfgelm_type_t)0; type < xbt_cfgelm_type_count && strcmp(tok, xbt_cfgelm_type_name[type]); increment(type));
+  xbt_assert(type < xbt_cfgelm_type_count,
+      "Invalid type in config element descriptor: %s; Should be one of 'string', 'int' or 'double'.", entry);
+
+  xbt_cfg_register(cfg, entrycpy, NULL, type, NULL);
+
+  free(entrycpy);               /* strdup'ed by dict mechanism, but cannot be const */
 }
 
-/** @brief Add a NULL-terminated list of pairs {(char*)key, value} to the set
- *
- * @param cfg config set to fill
- * @param name variable name
- * @param ... variable value
- */
-void xbt_cfg_set(xbt_cfg_t cfg, const char *name, ...)
+void xbt_cfg_aliases(void) { simgrid_config->showAliases(); }
+void xbt_cfg_help(void)    { simgrid_config->help(); }
+
+static simgrid::config::ConfigurationElement* xbt_cfgelm_get(xbt_cfg_t cfg, const char *name, e_xbt_cfgelm_type_t type)
 {
-  va_list pa;
+  simgrid::config::ConfigurationElement* res = (*cfg)[name];
 
-  va_start(pa, name);
-  xbt_cfg_set_vargs(cfg, name, pa);
-  va_end(pa);
+  if (!res) {
+    xbt_cfg_help();
+    fflush(stdout);
+    THROWF(not_found_error, 0, "No registered variable '%s' in this config set.", name);
+  }
+
+  xbt_assert(type == xbt_cfgelm_any || res->type == type,
+              "You tried to access to the config element %s as an %s, but its type is %s.",
+              name, xbt_cfgelm_type_name[type], xbt_cfgelm_type_name[res->type]);
+  return res;
 }
 
+/*----[ Setting ]---------------------------------------------------------*/
+
 /** @brief Add values parsed from a string into a config set
  *
  * @param options a string containing the content to add to the config set. This is a '\\t',' ' or '\\n' or ','
@@ -582,32 +537,16 @@ void xbt_cfg_set_parse(const char *options)
  * @return the first char after the parsed value in val
  */
 
-void *xbt_cfg_set_as_string(const char *key, const char *value) {
-  xbt_ex_t e;
+void *xbt_cfg_set_as_string(const char *key, const char *value)
+{
+  simgrid::config::ConfigurationElement* variable = (*simgrid_config)[key];
+  if (variable == nullptr)
+    THROWF(not_found_error, 0, "No registered variable corresponding to '%s'.", key);
 
   char *ret;
-  volatile xbt_cfgelm_t variable = NULL;
   int i;
   double d;
 
-  TRY {
-    while (variable == NULL) {
-      variable = (xbt_cfgelm_t) xbt_dict_get((xbt_dict_t) simgrid_config, key);
-      if (variable->type == xbt_cfgelm_alias) {
-        const char *newname = (const char*)variable->content;
-        XBT_INFO("Note: configuration '%s' is deprecated. Please use '%s' instead.", key, newname);
-        key = newname;
-        variable = NULL;
-      }
-    }
-  } CATCH(e) {
-    if (e.category == not_found_error) {
-      xbt_ex_free(e);
-      THROWF(not_found_error, 0, "No registered variable corresponding to '%s'.", key);
-    }
-    RETHROW;
-  }
-
   switch (variable->type) {
   case xbt_cfgelm_string:
     xbt_cfg_set_string(key, value);     /* throws */
@@ -644,11 +583,11 @@ void *xbt_cfg_set_as_string(const char *key, const char *value) {
  */
 void xbt_cfg_setdefault_int(const char *name, int val)
 {
-  xbt_cfgelm_t variable = xbt_cfgelm_get(simgrid_config, name, xbt_cfgelm_int);
+  simgrid::config::ConfigurationElement* variable = xbt_cfgelm_get(simgrid_config, name, xbt_cfgelm_int);
 
   if (variable->isdefault){
     xbt_cfg_set_int(name, val);
-    variable->isdefault = 1;
+    variable->isdefault = true;
   } else
     XBT_DEBUG("Do not override configuration variable '%s' with value '%d' because it was already set.", name, val);
 }
@@ -660,11 +599,11 @@ void xbt_cfg_setdefault_int(const char *name, int val)
  */
 void xbt_cfg_setdefault_double(const char *name, double val)
 {
-  xbt_cfgelm_t variable = xbt_cfgelm_get(simgrid_config, name, xbt_cfgelm_double);
+  simgrid::config::ConfigurationElement* variable = xbt_cfgelm_get(simgrid_config, name, xbt_cfgelm_double);
 
   if (variable->isdefault) {
     xbt_cfg_set_double(name, val);
-    variable->isdefault = 1;
+    variable->isdefault = true;
   } else
     XBT_DEBUG("Do not override configuration variable '%s' with value '%f' because it was already set.", name, val);
 }
@@ -676,11 +615,11 @@ void xbt_cfg_setdefault_double(const char *name, double val)
  */
 void xbt_cfg_setdefault_string(const char *name, const char *val)
 {
-  xbt_cfgelm_t variable = xbt_cfgelm_get(simgrid_config, name, xbt_cfgelm_string);
+  simgrid::config::ConfigurationElement* variable = xbt_cfgelm_get(simgrid_config, name, xbt_cfgelm_string);
 
   if (variable->isdefault){
     xbt_cfg_set_string(name, val);
-    variable->isdefault = 1;
+    variable->isdefault = true;
   } else
     XBT_DEBUG("Do not override configuration variable '%s' with value '%s' because it was already set.", name, val);
 }
@@ -692,11 +631,11 @@ void xbt_cfg_setdefault_string(const char *name, const char *val)
  */
 void xbt_cfg_setdefault_boolean(const char *name, const char *val)
 {
-  xbt_cfgelm_t variable = xbt_cfgelm_get(simgrid_config, name, xbt_cfgelm_boolean);
+  simgrid::config::ConfigurationElement* variable = xbt_cfgelm_get(simgrid_config, name, xbt_cfgelm_boolean);
 
   if (variable->isdefault){
     xbt_cfg_set_boolean(name, val);
-    variable->isdefault = 1;
+    variable->isdefault = true;
   }
    else
     XBT_DEBUG("Do not override configuration variable '%s' with value '%s' because it was already set.", name, val);
@@ -709,15 +648,11 @@ void xbt_cfg_setdefault_boolean(const char *name, const char *val)
  */
 void xbt_cfg_set_int(const char *name, int val)
 {
-  xbt_cfgelm_t variable = xbt_cfgelm_get(simgrid_config, name, xbt_cfgelm_int);
-
-  xbt_dynar_set(variable->content, 0, &val);
-
+  simgrid::config::ConfigurationElement* variable = xbt_cfgelm_get(simgrid_config, name, xbt_cfgelm_int);
+  variable->int_content = val;
   if (variable->cb_set)
     variable->cb_set(name);
-  if (variable->cb_set_ext)
-    variable->cb_set_ext(name, variable->cb_set_data);
-  variable->isdefault = 0;
+  variable->isdefault = false;
 }
 
 /** @brief Set or add a double value to \a name within \a cfg
@@ -727,15 +662,11 @@ void xbt_cfg_set_int(const char *name, int val)
  */
 void xbt_cfg_set_double(const char *name, double val)
 {
-  xbt_cfgelm_t variable = xbt_cfgelm_get(simgrid_config, name, xbt_cfgelm_double);
-
-  xbt_dynar_set(variable->content, 0, &val);
-
+  simgrid::config::ConfigurationElement* variable = xbt_cfgelm_get(simgrid_config, name, xbt_cfgelm_double);
+  variable->double_content = val;
   if (variable->cb_set)
     variable->cb_set(name);
-  if (variable->cb_set_ext)
-    variable->cb_set_ext(name, variable->cb_set_data);
-  variable->isdefault = 0;
+  variable->isdefault = false;
 }
 
 /** @brief Set or add a string value to \a name within \a cfg
@@ -747,21 +678,27 @@ void xbt_cfg_set_double(const char *name, double val)
  */
 void xbt_cfg_set_string(const char *name, const char *val)
 {
-  char *newval = xbt_strdup(val);
-  xbt_cfgelm_t variable = xbt_cfgelm_get(simgrid_config, name, xbt_cfgelm_string);
-
-  if (!xbt_dynar_is_empty(variable->content)) {
-    char *sval = xbt_dynar_get_as(variable->content, 0, char *);
-    free(sval);
-  }
-
-  xbt_dynar_set(variable->content, 0, &newval);
-
+  simgrid::config::ConfigurationElement* variable = xbt_cfgelm_get(simgrid_config, name, xbt_cfgelm_string);
+  free(variable->string_content);
+  variable->string_content = xbt_strdup(val);
   if (variable->cb_set)
     variable->cb_set(name);
-  if (variable->cb_set_ext)
-    variable->cb_set_ext(name, variable->cb_set_data);
-  variable->isdefault = 0;
+  variable->isdefault = false;
+
+  if (variable->callback) {
+    try {
+      variable->callback(val);
+    }
+    catch(std::range_error& e) {
+      xbt_die("Invalid flag %s=%s: %s", val, name, e.what());
+    }
+    catch(std::exception& e) {
+      xbt_die("Error for flag %s=%s: %s", val, name, e.what());
+    }
+    catch(...) {
+      xbt_die("Error for flag %s=%s", val, name);
+    }
+  }
 }
 
 /** @brief Set or add a boolean value to \a name within \a cfg
@@ -772,7 +709,7 @@ void xbt_cfg_set_string(const char *name, const char *val)
 void xbt_cfg_set_boolean(const char *name, const char *val)
 {
   int bval=-1;
-  xbt_cfgelm_t variable = xbt_cfgelm_get(simgrid_config, name, xbt_cfgelm_boolean);
+  simgrid::config::ConfigurationElement* variable = xbt_cfgelm_get(simgrid_config, name, xbt_cfgelm_boolean);
 
   for (int i = 0; xbt_cfgelm_boolean_values[i].true_val != NULL; i++) {
     if (strcmp(val, xbt_cfgelm_boolean_values[i].true_val) == 0){
@@ -785,20 +722,17 @@ void xbt_cfg_set_boolean(const char *name, const char *val)
     }
   }
   xbt_assert(bval != -1, "Value of option '%s' not valid. Should be a boolean (yes,no,on,off,true,false,0,1)", val);
-  xbt_dynar_set(variable->content, 0, &bval);
-
+  variable->boolean_content = bval;
   if (variable->cb_set)
     variable->cb_set(name);
-  if (variable->cb_set_ext)
-    variable->cb_set_ext(name, variable->cb_set_data);
-  variable->isdefault = 0;
+  variable->isdefault = false;
 }
 
 
 /* Say if the value is the default value */
 int xbt_cfg_is_default_value(const char *name)
 {
-  xbt_cfgelm_t variable = xbt_cfgelm_get(simgrid_config, name, xbt_cfgelm_any);
+  simgrid::config::ConfigurationElement* variable = xbt_cfgelm_get(simgrid_config, name, xbt_cfgelm_any);
   return variable->isdefault;
 }
 
@@ -808,18 +742,11 @@ int xbt_cfg_is_default_value(const char *name)
  * @param name the name of the variable
  *
  * Returns the first value from the config set under the given name.
- * If there is more than one value, it will issue a warning. Consider using xbt_cfg_get_dynar() instead.
  */
 int xbt_cfg_get_int(const char *name)
 {
-  xbt_cfgelm_t variable = xbt_cfgelm_get(simgrid_config, name, xbt_cfgelm_int);
-
-  if (xbt_dynar_length(variable->content) > 1) {
-    XBT_WARN("You asked for the first value of the config element '%s', but there is %lu values",
-         name, xbt_dynar_length(variable->content));
-  }
-
-  return xbt_dynar_get_as(variable->content, 0, int);
+  simgrid::config::ConfigurationElement* variable = xbt_cfgelm_get(simgrid_config, name, xbt_cfgelm_int);
+  return variable->int_content;
 }
 
 /** @brief Retrieve a double value of a variable (get a warning if not uniq)
@@ -828,18 +755,11 @@ int xbt_cfg_get_int(const char *name)
  * @param name the name of the variable
  *
  * Returns the first value from the config set under the given name.
- * If there is more than one value, it will issue a warning. Consider using xbt_cfg_get_dynar() instead.
  */
 double xbt_cfg_get_double(const char *name)
 {
-  xbt_cfgelm_t variable = xbt_cfgelm_get(simgrid_config, name, xbt_cfgelm_double);
-
-  if (xbt_dynar_length(variable->content) > 1) {
-    XBT_WARN ("You asked for the first value of the config element '%s', but there is %lu values\n",
-         name, xbt_dynar_length(variable->content));
-  }
-
-  return xbt_dynar_get_as(variable->content, 0, double);
+  simgrid::config::ConfigurationElement* variable = xbt_cfgelm_get(simgrid_config, name, xbt_cfgelm_double);
+  return variable->double_content;
 }
 
 /** @brief Retrieve a string value of a variable (get a warning if not uniq)
@@ -848,23 +768,15 @@ double xbt_cfg_get_double(const char *name)
  * @param name the name of the variable
  *
  * Returns the first value from the config set under the given name.
- * If there is more than one value, it will issue a warning. Consider using
- * xbt_cfg_get_dynar() instead. Returns NULL if there is no value.
+ * If there is more than one value, it will issue a warning.
+ * Returns NULL if there is no value.
  *
  * \warning the returned value is the actual content of the config set
  */
 char *xbt_cfg_get_string(const char *name)
 {
-  xbt_cfgelm_t variable = xbt_cfgelm_get(simgrid_config, name, xbt_cfgelm_string);
-
-  if (xbt_dynar_length(variable->content) > 1) {
-    XBT_WARN("You asked for the first value of the config element '%s', but there is %lu values\n",
-         name, xbt_dynar_length(variable->content));
-  } else if (xbt_dynar_is_empty(variable->content)) {
-    return NULL;
-  }
-
-  return xbt_dynar_get_as(variable->content, 0, char *);
+  simgrid::config::ConfigurationElement* variable = xbt_cfgelm_get(simgrid_config, name, xbt_cfgelm_string);
+  return variable->string_content;
 }
 
 /** @brief Retrieve a boolean value of a variable (get a warning if not uniq)
@@ -873,50 +785,81 @@ char *xbt_cfg_get_string(const char *name)
  * @param name the name of the variable
  *
  * Returns the first value from the config set under the given name.
- * If there is more than one value, it will issue a warning. Consider using xbt_cfg_get_dynar() instead.
+ * If there is more than one value, it will issue a warning.
  */
 int xbt_cfg_get_boolean(const char *name)
 {
-  xbt_cfgelm_t variable = xbt_cfgelm_get(simgrid_config, name, xbt_cfgelm_boolean);
-
-  if (xbt_dynar_length(variable->content) > 1) {
-    XBT_WARN("You asked for the first value of the config element '%s', but there is %lu values",
-         name, xbt_dynar_length(variable->content));
-  }
-
-  return xbt_dynar_get_as(variable->content, 0, int);
+  simgrid::config::ConfigurationElement* variable = xbt_cfgelm_get(simgrid_config, name, xbt_cfgelm_boolean);
+  return variable->boolean_content;
 }
 
 namespace simgrid {
 namespace config {
 
-static void callCallback(const char* name, void* data)
+bool parseBool(const char* value)
 {
-  (*(std::function<void(const char*)>*) data)(name);
-}
-
-static void freeCallback(void* data)
-{
-  delete (std::function<void(const char*)>*) data;
+  for (int i = 0; xbt_cfgelm_boolean_values[i].true_val != NULL; i++) {
+    if (std::strcmp(value, xbt_cfgelm_boolean_values[i].true_val) == 0)
+      return true;
+    if (std::strcmp(value, xbt_cfgelm_boolean_values[i].false_val) == 0)
+      return false;
+  }
+  throw std::range_error("not a boolean");
+}
+
+double parseDouble(const char* value)
+{
+  char* end;
+  errno = 0;
+  double res = std::strtod(value, &end);
+  if (errno == ERANGE)
+    throw std::range_error("out of range");
+  else if (errno)
+    xbt_die("Unexpected errno");
+  if (end == value || *end != '\0')
+    throw std::range_error("invalid double");
+  else
+    return res;
+}
+
+long int parseLong(const char* value)
+{
+  char* end;
+  errno = 0;
+  long int res = std::strtol(value, &end, 0);
+  if (errno) {
+    if (res == LONG_MIN && errno == ERANGE)
+      throw std::range_error("underflow");
+    else if (res == LONG_MAX && errno == ERANGE)
+      throw std::range_error("overflow");
+    xbt_die("Unexpected errno");
+  }
+  if (end == value || *end != '\0')
+    throw std::range_error("invalid integer");
+  else
+    return res;
 }
 
-void registerConfig(const char* name, const char* description,
-  e_xbt_cfgelm_type_t type,
-  std::function<void(const char*)> callback)
+void declareFlag(const char* name, const char* description,
+  std::function<void(const char* value)> callback)
 {
-  std::function<void(const char*)>* code
-    = new std::function<void(const char*)>(std::move(callback));
-  xbt_cfg_register_ext(name, description, type,
-    callCallback, code, freeCallback);
+  simgrid::config::ConfigurationElement* e = xbt_cfg_register(
+    &simgrid_config, name, description, xbt_cfgelm_string, NULL);
+  e->callback = std::move(callback);
 }
 
 }
 }
 
 #ifdef SIMGRID_TEST
+
+#include <string>
+
 #include "xbt.h"
 #include "xbt/ex.h"
 
+#include <xbt/config.hpp>
+
 XBT_LOG_EXTERNAL_DEFAULT_CATEGORY(xbt_cfg);
 
 XBT_TEST_SUITE("config", "Configuration support");
@@ -971,4 +914,27 @@ XBT_TEST_UNIT("use", test_config_use, "Data retrieving tests")
   }
   xbt_cfg_free(&simgrid_config);
 }
+
+XBT_TEST_UNIT("c++flags", test_config_cxx_flags, "C++ flags")
+{
+  simgrid_config = make_set();
+  xbt_test_add("C++ declaration of flags");
+
+  simgrid::config::Flag<int> int_flag("int", "", 0);
+  simgrid::config::Flag<std::string> string_flag("string", "", "foo");
+  simgrid::config::Flag<double> double_flag("double", "", 0.32);
+  simgrid::config::Flag<bool> bool_flag1("bool1", "", false);
+  simgrid::config::Flag<bool> bool_flag2("bool2", "", true);
+
+  xbt_test_add("Parse values");
+  xbt_cfg_set_parse("int:42 string:bar double:8.0 bool1:true bool2:false");
+  xbt_test_assert(int_flag == 42, "Check int flag");
+  xbt_test_assert(string_flag == "bar", "Check string flag");
+  xbt_test_assert(double_flag == 8.0, "Check double flag");
+  xbt_test_assert(bool_flag1, "Check bool1 flag");
+  xbt_test_assert(!bool_flag2, "Check bool2 flag");
+
+  xbt_cfg_free(&simgrid_config);
+}
+
 #endif                          /* SIMGRID_TEST */