diff --git a/src/schema/TODO.md b/src/schema/TODO.md
index 1aea69f..46e80ce 100644
--- a/src/schema/TODO.md
+++ b/src/schema/TODO.md
@@ -1,6 +1,5 @@
 # nulib\schema
 
-* renommer AnalyzerContext en WrapperContext
 * plus de {key} ni {orig} dans messages
   * les messages standard ne sont utilisés que s'il n'y a pas de message dans
     l'exception
@@ -14,32 +13,6 @@
 * tdate et tdatetime. qu'en est-il des autres classes (delay, etc.)
   * possibilité de spécifier le format de la date à analyser 
 * ScalarSchema::from_property()
-* possibilité de spécifier un type via sa classe, e.g
-  ~~~php
-  Schema::ns($schema, [
-    MyType::class, null, "une valeur de type MyType"
-  ]);
-  # ou
-  Schema::ns($schema, [
-    [MyType::class => $params], null, "une valeur de type MyType"
-  ]);
-  ~~~
-  MyType doit implémenter IType
-* possibilité de spécifier une instance de type, e.g
-  ~~~php
-  Schema::ns($schema, [
-    new MyType(), null, "une valeur de type MyType"
-  ]);
-  ~~~
-  MyType doit implémenter IType
-* type générique construit à partir d'un nom de classe, e.g
-  ~~~php
-  Schema::ns($schema, [
-    MyClass::class, null, "une valeur de type MyClass"
-  ]);
-  ~~~
-  MyClass ne doit pas implémenter IType, et le type correspondant est créé avec
-  `new tgeneric(MyClass::class)`
 
 * dans AssocSchema, support `[key_prefix]` qui permet de spécifier un préfixe
   commun aux champs dans le tableau destination, e.g
diff --git a/src/schema/AnalyzerContext.php b/src/schema/WrapperContext.php
similarity index 96%
rename from src/schema/AnalyzerContext.php
rename to src/schema/WrapperContext.php
index 3136c04..5ee0d37 100644
--- a/src/schema/AnalyzerContext.php
+++ b/src/schema/WrapperContext.php
@@ -4,7 +4,7 @@ namespace nur\sery\wip\schema;
 use nur\sery\wip\schema\input\Input;
 use nur\sery\wip\schema\types\IType;
 
-class AnalyzerContext {
+class WrapperContext {
   function __construct(Schema $schema, Wrapper $wrapper, Input $input, $valueKey, Result $result) {
     $this->schema = $schema;
     $this->wrapper = $wrapper;
diff --git a/src/schema/_scalar/ScalarWrapper.php b/src/schema/_scalar/ScalarWrapper.php
index bfd0a81..0ea9596 100644
--- a/src/schema/_scalar/ScalarWrapper.php
+++ b/src/schema/_scalar/ScalarWrapper.php
@@ -4,7 +4,7 @@ namespace nur\sery\wip\schema\_scalar;
 use nulib\php\func;
 use nulib\ref\schema\ref_analyze;
 use nulib\ValueException;
-use nur\sery\wip\schema\AnalyzerContext;
+use nur\sery\wip\schema\WrapperContext;
 use nur\sery\wip\schema\input\Input;
 use nur\sery\wip\schema\types;
 use nur\sery\wip\schema\types\IType;
@@ -74,7 +74,7 @@ class ScalarWrapper extends Wrapper {
   }
 
   /** analyser la valeur et résoudre son type */
-  protected function analyze0(AnalyzerContext $context): int {
+  protected function analyze0(WrapperContext $context): int {
     /** @var ScalarSchema $schema */
     $schema = $context->schema;
     $input = $context->input;
@@ -171,7 +171,7 @@ class ScalarWrapper extends Wrapper {
     $valueKey = $this->valueKey;
     $result = $this->result;
     $result->reset();
-    $context = new AnalyzerContext($schema, $this, $input, $valueKey, $result);
+    $context = new WrapperContext($schema, $this, $input, $valueKey, $result);
 
     /** @var func $analyzerFunc */
     $analyzerFunc = $schema->analyzerFunc;
@@ -243,7 +243,7 @@ class ScalarWrapper extends Wrapper {
       /** @var func $normalizerFunc */
       $normalizerFunc = $schema->normalizerFunc;
       if ($normalizerFunc !== null) {
-        $context = new AnalyzerContext($schema, $this, $this->input, $valueKey, $result);
+        $context = new WrapperContext($schema, $this, $this->input, $valueKey, $result);
         $orig = $value;
         $value = $normalizerFunc->invoke([$orig, $context]);
         $modified = $value !== $orig;
diff --git a/src/schema/types.php b/src/schema/types.php
index 7e3442a..c1b618b 100644
--- a/src/schema/types.php
+++ b/src/schema/types.php
@@ -1,6 +1,7 @@
 <?php
 namespace nur\sery\wip\schema;
 
+use nulib\ValueException;
 use nur\sery\wip\schema\types\IType;
 use nur\sery\wip\schema\types\Registry;
 use nur\sery\wip\schema\types\tarray;
@@ -31,7 +32,11 @@ class types {
     return self::$registry;
   }
 
-  static function get(bool $nullable, ?string $name, ?array $args=null, ?array $definition=null): IType {
+  static function get(bool $nullable, $name, ?array $args=null, ?array $definition=null): IType {
+    if ($name instanceof IType) return $name;
+    if ($name !== null && !is_string($name)) {
+      throw ValueException::invalid_type($name, "string");
+    }
     return self::registry()->get($nullable, $name, $args, $definition);
   }
 
diff --git a/src/schema/types/IType.php b/src/schema/types/IType.php
index a245fd7..36f5fd4 100644
--- a/src/schema/types/IType.php
+++ b/src/schema/types/IType.php
@@ -10,6 +10,8 @@ use nur\sery\wip\schema\Schema;
  * Interface IType: un type de données
  */
 interface IType {
+  static function get_params_from_definition(?array $definition): ?array;
+
   /**
    * obtenir, pour information, le nom officiel de ce type, utilisable dans une
    * définition de schéma
diff --git a/src/schema/types/Registry.php b/src/schema/types/Registry.php
index eb16596..e7bdecd 100644
--- a/src/schema/types/Registry.php
+++ b/src/schema/types/Registry.php
@@ -3,6 +3,7 @@ namespace nur\sery\wip\schema\types;
 
 use nulib\cl;
 use nulib\php\func;
+use nulib\ValueException;
 
 class Registry {
   const TYPES = [
@@ -31,8 +32,6 @@ class Registry {
   protected $types;
 
   function get(bool $nullable, ?string $name, ?array $args=null, ?array $definition=null): IType {
-    $name ??= "raw";
-    $class = self::TYPES[$name];
     if (cl::is_list($args)) {
       $key = array_key_last($args);
       $params = $args[$key];
@@ -41,6 +40,16 @@ class Registry {
       $params = $args;
       $args = null;
     }
+    $name ??= "raw";
+    $class = cl::get(self::TYPES, $name);
+    if ($class === null) {
+      $class = $name;
+      if (!class_exists($class)) {
+        throw ValueException::invalid_type($class, IType::class);
+      } elseif (!is_subclass_of($class, IType::class)) {
+        return new tgeneric($class, $nullable, $params);
+      }
+    }
     $params = cl::merge($class::get_params_from_definition($definition), $params);
     if ($args || $params !== null) {
       $args ??= [];
diff --git a/src/schema/types/tgeneric.php b/src/schema/types/tgeneric.php
new file mode 100644
index 0000000..16f86a8
--- /dev/null
+++ b/src/schema/types/tgeneric.php
@@ -0,0 +1,52 @@
+<?php
+namespace nur\sery\wip\schema\types;
+
+use nulib\ValueException;
+use nur\sery\wip\schema\_scalar\ScalarResult;
+use nur\sery\wip\schema\_scalar\ScalarSchema;
+use nur\sery\wip\schema\input\Input;
+use nur\sery\wip\schema\Result;
+use nur\sery\wip\schema\Schema;
+
+class tgeneric extends _tsimple {
+  function __construct(string $class, bool $nullable, ?array $params=null) {
+    $this->class = $class;
+    parent::__construct($nullable, $params);
+  }
+
+  protected string $class;
+
+  function getClass(): string {
+    return $this->class;
+  }
+
+  function isAvailable(Input $input, $valueKey): bool {
+    return $input->isAvailable($valueKey);
+  }
+
+  public function isNull($value): bool {
+    return $value === null;
+  }
+
+  function isValid($value, ?bool &$normalized=null): bool {
+    $normalized = true;
+    return $value instanceof $this->class;
+  }
+
+  function parse(string $value) {
+    throw ValueException::invalid_type($value, $this->class);
+  }
+
+  /**
+   * @var ScalarResult $result
+   * @var ScalarSchema $schema
+   */
+  function verifix(&$value, Result $result, Schema $schema): bool {
+    $result->setNormalized();
+    return false;
+  }
+
+  function format($value, $format=null): string {
+    return strval($value);
+  }
+}
diff --git a/src/schema/types/tmixed.php b/src/schema/types/tmixed.php
index 5f387c6..fa525eb 100644
--- a/src/schema/types/tmixed.php
+++ b/src/schema/types/tmixed.php
@@ -41,6 +41,6 @@ class tmixed extends _tsimple {
   }
 
   function format($value, $format=null): string {
-    return var_export($value, true);
+    return strval($value);
   }
 }