diff --git a/src/app/cli/ArgDef.php b/src/app/cli/ArgDef.php
index 9664d36..fa508bc 100644
--- a/src/app/cli/ArgDef.php
+++ b/src/app/cli/ArgDef.php
@@ -7,7 +7,7 @@ use nulib\php\func;
 use nulib\php\types\varray;
 use nulib\php\types\vbool;
 
-class ArgDef {
+class ArgDef implements IArgo {
   const TYPE_SHORT = 0, TYPE_LONG = 1, TYPE_COMMAND = 2;
   const ARGS_NONE = 0, ARGS_MANDATORY = 1, ARGS_OPTIONAL = 2;
   const ACTION_SET = 0, ACTION_INC = 1, ACTION_DEC = 2, ACTION_FUNC = 3;
@@ -119,6 +119,10 @@ class ArgDef {
     else return array_keys($this->options);
   }
 
+  function isEmpty(): bool {
+    return $this->disabled || !boolval($this->options);
+  }
+
   /** traiter le paramètre parent */
   function processOptions(): void {
     $this->removeOptions($this->removes);
@@ -433,17 +437,16 @@ class ArgDef {
     return [
       ...$this->getOptions(),
       "empty" => $this->isEmpty(),
-      "help" => $this->help,
-      "have_short_options" => $this->haveShortOptions,
-      "have_long_options" => $this->haveLongOptions,
-      "is_command" => $this->isCommand,
-      "is_help" => $this->isHelp,
-      "is_remains" => $this->isRemains,
-      "ĥave_args" => $this->haveArgs,
-      "min_args" => $this->minArgs,
-      "max_args" => $this->maxArgs,
-      "args" => $this->args,
-      "argsdesc" => $this->argsdesc,
+      //"help" => $this->help,
+      //"have_short_options" => $this->haveShortOptions,
+      //"have_long_options" => $this->haveLongOptions,
+      //"is_command" => $this->isCommand,
+      //"is_help" => $this->isHelp,
+      //"is_remains" => $this->isRemains,
+      //"ĥave_args" => $this->haveArgs,
+      //"min_args" => $this->minArgs,
+      //"max_args" => $this->maxArgs,
+      //"argsdesc" => $this->argsdesc,
     ];
   }
 }
diff --git a/src/app/cli/ArgDefs.php b/src/app/cli/ArgDefs.php
index 7d4d648..9944349 100644
--- a/src/app/cli/ArgDefs.php
+++ b/src/app/cli/ArgDefs.php
@@ -3,60 +3,61 @@ namespace nulib\app\cli;
 
 use nulib\cl;
 
-abstract class ArgDefs {
+abstract class ArgDefs implements IArgo {
   function __construct(array $defs) {
     $this->defs = $defs;
-    $this->mergeParse($defs, $argDefs);
-    $this->addAll($argDefs);
+    $this->mergeParse($defs, $argos);
+    $this->setArgos($argos);
   }
 
   protected array $defs;
 
-  protected function mergeParse(array $defs, ?array &$argDefs, bool $parse=true): void {
+  protected function mergeParse(array $defs, ?array &$argos, bool $parse=true): void {
     $defaults = $defs["defaults"] ?? null;
     if ($defaults !== null) {
-      $this->mergeParse($defaults, $argDefs, false);
-      $this->parse($defaults, $argDefs);
+      $this->mergeParse($defaults, $argos, false);
+      $this->parse($defaults, $argos);
     }
 
-    if ($parse) $this->parse($defs, $argDefs);
+    if ($parse) $this->parse($defs, $argos);
 
     $merges = $defs["merges"] ?? null;
     $merge = $defs["merge"] ?? null;
     if ($merge !== null) $merges[] = $merge;
     if ($merges !== null) {
       foreach ($merges as $merge) {
-        $this->mergeParse($merge, $argDefs, false);
-        $this->parse($merge, $argDefs);
+        $this->mergeParse($merge, $argos, false);
+        $this->parse($merge, $argos);
       }
     }
   }
 
+  protected function parse(array $defs, ?array &$argos): void {
+    [$defs, $params] = cl::split_assoc($defs);
+    foreach ($defs as $def) {
+      $argos[] = new ArgDef($def);
+    }
+    $this->parseParams($params);
+  }
+
   protected function parseParams(?array $params): void {
   }
 
-  protected function parse(array $defs, ?array &$argDefs): void {
-    [$defs, $params] = cl::split_assoc($defs);
-    foreach ($defs as $def) {
-      $argDefs[] = new ArgDef($def);
-    }
-    $this->parseParams($params);
+  protected array $argos;
+
+  function getArgos(): array {
+    return $this->argos;
   }
 
-  protected array $all;
-
-  protected function addAll(?array $argDefs): void {
-    $this->all = $argDefs ?? [];
-  }
-
-  function all(): array {
-    return array_filter($this->all, function (ArgDef $argDef) {
-      return !$argDef->isEmpty();
+  protected function setArgos(?array $argos): void {
+    $argos ??= [];
+    $this->argos = array_filter($argos, function (IArgo $argo): bool {
+      return !$argo->isEmpty();
     });
   }
 
   function isEmpty(): bool {
-    return !$this->all();
+    return !$this->getArgos();
   }
 
   function get(string $option): ?ArgDef {
@@ -117,4 +118,10 @@ abstract class ArgDefs {
   function normalize(array $args): array {
     return $args;
   }
+
+  function debugInfos(): array {
+    return array_map(function (IArgo $argo) {
+      return $argo->debugInfos();
+    }, $this->argos);
+  }
 }
diff --git a/src/app/cli/IArgo.php b/src/app/cli/IArgo.php
new file mode 100644
index 0000000..d8a2158
--- /dev/null
+++ b/src/app/cli/IArgo.php
@@ -0,0 +1,11 @@
+<?php
+namespace nulib\app\cli;
+
+/**
+ * Interface IArgo: une instance de ArgDef, ArgGroup ou ArgSection
+ */
+interface IArgo {
+  function isEmpty(): bool;
+
+  function debugInfos(): array;
+}
diff --git a/src/app/cli/SimpleArgDefs.php b/src/app/cli/SimpleArgDefs.php
index df19842..a49e887 100644
--- a/src/app/cli/SimpleArgDefs.php
+++ b/src/app/cli/SimpleArgDefs.php
@@ -55,57 +55,62 @@ class SimpleArgDefs extends ArgDefs {
 
   protected array $index;
 
-  protected function addAll(?array $argDefs): void {
-    parent::addAll($argDefs);
-    $this->index = [];
-    if ($argDefs !== null) {
-      # calculer les options pour les objets déjà fusionnés puis indexer une
-      # première fois
-      foreach ($argDefs as $argDef) {
-        /** @var ArgDef $argDef */
-        if (!$argDef->isExtends()) {
-          $argDef->processOptions();
-        }
-      }
-      $this->index = [];
-      foreach ($argDefs as $argDef) {
-        if ($argDef->isExtends()) continue;
-        $options = $argDef->getOptions();
-        foreach ($options as $option) {
-          /** @var ArgDef $prevArgDef */
-          $prevArgDef = $this->index[$option] ?? null;
-          if ($prevArgDef !== null) $prevArgDef->removeOption($option);
-          $this->index[$option] = $argDef;
-        }
-      }
+  protected function setArgos(?array $argos): void {
+    $argos ??= [];
 
-      # puis traiter les extensions d'objets, calculer les options pour ces
-      # objets et indexer pour la deuxième fois
-      foreach ($argDefs as $argDef) {
-        /** @var ArgDef $argDef */
-        if ($argDef->isExtends()) {
-          $argDef->processExtends($this);
-        }
-      }
-      $this->index = [];
-      foreach ($argDefs as $argDef) {
-        if ($argDef->isExtends()) continue;
-        $options = $argDef->getOptions();
-        foreach ($options as $option) {
-          /** @var ArgDef $prevArgDef */
-          $prevArgDef = $this->index[$option] ?? null;
-          if ($prevArgDef !== null) $prevArgDef->removeOption($option);
-          $this->index[$option] = $argDef;
-        }
-      }
-
-      # puis calculer nombre d'arguments et actions
-      foreach ($argDefs as $argDef) {
-        if ($argDef->isExtends()) continue;
-        $argDef->processArgs();
-        $argDef->processAction();
+    # calculer les options pour les objets déjà fusionnés puis indexer une
+    # première fois
+    foreach ($argos as $argo) {
+      /** @var ArgDef $argo */
+      if (!$argo->isExtends()) {
+        $argo->processOptions();
       }
     }
+    $this->index = [];
+    foreach ($argos as $argo) {
+      if ($argo->isExtends()) continue;
+      $options = $argo->getOptions();
+      foreach ($options as $option) {
+        /** @var ArgDef $prevArgo */
+        $prevArgo = $this->index[$option] ?? null;
+        if ($prevArgo !== null) $prevArgo->removeOption($option);
+        $this->index[$option] = $argo;
+      }
+    }
+
+    # puis traiter les extensions d'objets, calculer les options pour ces
+    # objets et indexer pour la deuxième fois
+    foreach ($argos as $argo) {
+      /** @var ArgDef $argo */
+      if ($argo->isExtends()) {
+        $argo->processExtends($this);
+      }
+    }
+    $this->index = [];
+    foreach ($argos as $argo) {
+      if ($argo->isExtends()) continue;
+      $options = $argo->getOptions();
+      foreach ($options as $option) {
+        /** @var ArgDef $prevArgo */
+        $prevArgo = $this->index[$option] ?? null;
+        if ($prevArgo !== null) $prevArgo->removeOption($option);
+        $this->index[$option] = $argo;
+      }
+    }
+
+    # ne garder que les objets non vides
+    $argos = array_filter($argos, function(IArgo $argo): bool {
+      return !$argo->isEmpty();
+    });
+
+    # puis calculer nombre d'arguments et actions
+    foreach ($argos as $argo) {
+      if ($argo->isExtends()) continue;
+      $argo->processArgs();
+      $argo->processAction();
+    }
+
+    $this->argos = $argos;
   }
 
   function get(string $option): ?ArgDef {
@@ -260,4 +265,15 @@ class SimpleArgDefs extends ArgDefs {
     }
     return array_merge($options, ["--"], $remains);
   }
+
+  function debugInfos(): array {
+    return [
+      "argos" => array_map(function (IArgo $argo) {
+        return $argo->debugInfos();
+      }, $this->argos),
+      "index" => array_map(function (IArgo $argo) {
+        return $argo->debugInfos();
+      }, $this->index),
+    ];
+  }
 }
diff --git a/src/app/cli/TODO.md b/src/app/cli/TODO.md
index 44c1be5..7f3a2c1 100644
--- a/src/app/cli/TODO.md
+++ b/src/app/cli/TODO.md
@@ -4,8 +4,6 @@
 * [x] pour le nombre d'arguments, supporter l'alias `*` pour `0..N` et `+` pour `1..N`
 * [ ] transformer un schéma en définition d'arguments, un tableau en liste d'arguments, et vice-versa
 
-lors de la surcharge d'une définition d'option, certaines options sont supprimées. quand toutes les options sont supprimées, la définition disparait.
-
 faire une implémentation SimpleArgsParser qui ne supporte pas les commandes, uniquement les options
 
 puis faire une implémentation ArgsParser qui supporte les commandes, et les options dynamiques
diff --git a/tests/app/cli/ArgDefTest.php b/tests/app/cli/ArgDefTest.php
index 074b7d9..d84a787 100644
--- a/tests/app/cli/ArgDefTest.php
+++ b/tests/app/cli/ArgDefTest.php
@@ -157,6 +157,31 @@ class ArgDefTest extends TestCase {
       false, 0, 0, "");
   }
 
+  function testOverride() {
+    $argDefs = new SimpleArgDefs([
+      ["-o", "--longx"],
+      "merge" => [
+        ["-o", "--longo"],
+      ],
+    ]);
+    var_export($argDefs->debugInfos()); #XXX
+
+    $argDefs = new SimpleArgDefs([
+      ["-o", "--longo"],
+      ["-o", "--longx"],
+    ]);
+    var_export($argDefs->debugInfos()); #XXX
+
+    $argDefs = new SimpleArgDefs([
+      ["-o", "--longo"],
+      ["-o"],
+      ["--longo"],
+    ]);
+    var_export($argDefs->debugInfos()); #XXX
+
+    self::assertTrue(true);
+  }
+
   function testExtends() {
     $ARGS1 = [
       ["-o:", "--longo",
@@ -176,8 +201,11 @@ class ArgDefTest extends TestCase {
         "help" => "help desta"
       ],
     ];
-    $argDefs1 = new SimpleArgDefs($ARGS1);
+    //$argDefs1 = new SimpleArgDefs($ARGS1);
+    //var_export($argDefs1->debugInfos()); #XXX
     $argDefs2 = new SimpleArgDefs($ARGS2);
+    var_export($argDefs2->debugInfos()); #XXX
+
     self::assertTrue(true);
   }
 }