diff --git a/src/schema/TODO.md b/src/schema/TODO.md
index dea7216..5c1bf19 100644
--- a/src/schema/TODO.md
+++ b/src/schema/TODO.md
@@ -1,14 +1,19 @@
 # nulib\schema
 
+* dans la définition, `[type]` est remplacé par l'instance de IType lors de sa
+  résolution? --> NON, sauf si c'est un type union
+* newInput dans Schema
+* ScalarSchema::from_property()
+
 * dans AssocSchema, support `[key_prefix]` qui permet de spécifier un préfixe
   commun aux champs dans le tableau destination, e.g
   ~~~php
-  $value = Schema::ns($schema, [
+  $wrapper = Schema::ns($schema, [
     "a" => "?string",
     "b" => "?int",
-  ])->newValue();
+  ])->newWrapper();
   $dest = ["x_a" => 5, "x_b" => "10"],
-  $value->reset($dest, null, [
+  $wrapper->reset($dest, null, [
     "key_prefix" => "x_",
   ]);
   # $dest vaut ["x_a" => "5", "x_b" => 10];
@@ -19,18 +24,16 @@
   alternative: c'est lors de la *définition* du schéma que le préfixe est ajouté
   e.g
   ~~~php
-  $value = Schema::ns($schema, [
+  $wrapper = Schema::ns($schema, [
     "a" => "?string",
     "b" => "?int",
   ], [
     "key_prefix" => "x_",
-  ])->newValue();
+  ])->newWrapper();
   $dest = ["x_a" => 5, "x_b" => "10"],
-  $value->reset($dest);
+  $wrapper->reset($dest);
   # $dest vaut ["x_a" => "5", "x_b" => 10];
   ~~~
-* dans la définition, `[type]` est remplacé par l'instance de IType lors de sa
-  résolution?
 * implémenter l'instanciation de types avec des paramètres particuliers. *si*
   des paramètres sont fournis, le type est instancié avec la signature 
   `IType($typeDefinition, $schemaDefinition)` e.g
diff --git a/src/schema/_scalar/ScalarResult.php b/src/schema/_scalar/ScalarResult.php
index 1ef71ee..b247aba 100644
--- a/src/schema/_scalar/ScalarResult.php
+++ b/src/schema/_scalar/ScalarResult.php
@@ -1,11 +1,13 @@
 <?php
 namespace nur\sery\wip\schema\_scalar;
 
+use Exception;
 use nulib\cl;
 use nulib\ref\schema\ref_analyze;
 use nulib\ref\schema\ref_schema;
 use nulib\ValueException;
 use nur\sery\wip\schema\Result;
+use Throwable;
 
 /**
  * Class ScalarResult: résultat de l'analyse ou de la normalisation d'une valeur
@@ -16,12 +18,20 @@ use nur\sery\wip\schema\Result;
  * @property bool $null si la valeur est disponible, est-elle nulle?
  * @property bool $valid si la valeur est disponible, est-elle valide?
  * @property bool $normalized si la valeur est valide, est-elle normalisée?
- * @property string|null $orig valeur originale avant extraction et analyse
  * @property string|null $messageKey clé de message si la valeur n'est pas valide
  * @property string|null $message message si la valeur n'est pas valide
+ * @property string|null $origValue valeur originale avant extraction et analyse
+ * @property mixed|null $normalizedValue la valeur normalisée si elle est
+ * disponible, null sinon. ce champ est utilisé comme optimisation si la valeur
+ * normalisée a déjà été calculée
  */
 class ScalarResult extends Result {
-  const KEYS = ["resultAvailable", "present", "available", "null", "valid", "normalized", "orig", "messageKey", "message"];
+  const KEYS = [
+    "resultAvailable",
+    "present", "available", "null", "valid", "normalized",
+    "messageKey", "message",
+    "origValue", "normalizedValue",
+  ];
 
   function isScalar(?ScalarResult &$scalar=null): bool { $scalar = $this; return true; }
 
@@ -66,8 +76,8 @@ class ScalarResult extends Result {
     }
   }
 
-  protected static function replace_orig(string &$message, $orig): void {
-    $message = str_replace("{orig}", strval($orig), $message);
+  protected static function replace_orig(string &$message, $origValue): void {
+    $message = str_replace("{orig}", strval($origValue), $message);
   }
 
   protected function getMessage(string $key, ScalarSchema $schema): string {
@@ -130,27 +140,32 @@ class ScalarResult extends Result {
     }
   }
 
-  function setInvalid($value, ScalarSchema $schema): int {
+  function setInvalid($value, ScalarSchema $schema, ?Throwable $t=null): int {
     $this->resultAvailable = true;
     $this->present = true;
     $this->available = true;
     $this->null = false;
     $this->valid = false;
-    $this->orig = $value;
+    $this->origValue = $value;
     $messageKey = $this->messageKey = "invalid";
     $message = $this->getMessage($messageKey, $schema);
     self::replace_key($message, $schema->name);
     self::replace_orig($message, $schema->orig);
+    if ($t !== null) {
+      $tmessage = ValueException::get_message($t);
+      if ($tmessage) $message .= ": $tmessage";
+    }
     $this->message = $message;
     return ref_analyze::INVALID;
   }
 
-  function setValid(): int {
+  function setValid($normalizedValue=null): int {
     $this->resultAvailable = true;
     $this->present = true;
     $this->available = true;
     $this->null = false;
     $this->valid = true;
+    $this->normalizedValue = $normalizedValue;
     return ref_analyze::VALID;
   }
 
diff --git a/src/schema/_scalar/ScalarWrapper.php b/src/schema/_scalar/ScalarWrapper.php
index 00a40b2..13c3d9f 100644
--- a/src/schema/_scalar/ScalarWrapper.php
+++ b/src/schema/_scalar/ScalarWrapper.php
@@ -9,22 +9,23 @@ use nur\sery\wip\schema\input\Input;
 use nur\sery\wip\schema\types;
 use nur\sery\wip\schema\types\IType;
 use nur\sery\wip\schema\Wrapper;
+use PHPUnit\Event\Code\Throwable;
 
 class ScalarWrapper extends Wrapper {
   function __construct(ScalarSchema $schema, &$dest=null, $destKey=null, ?array $params=null) {
-    $defaultVerifix = $params["verifix"] ?? true;
-    $defaultThrow = $params["throw"] ?? null;
-    if ($dest !== null && $defaultThrow === null) {
+    $verifix = $params["verifix"] ?? true;
+    $throw = $params["throw"] ?? null;
+    if ($dest !== null && $throw === null) {
       # Si $dest est null, ne pas lancer d'exception, parce qu'on considère que
       # c'est une initialisation sans conséquences
-      $defaultThrow = true;
+      $throw = true;
     }
     $this->schema = $schema;
-    $this->verifix = $defaultVerifix;
-    $this->throw = $defaultThrow ?? false;
+    $this->verifix = $verifix;
+    $this->throw = $throw ?? false;
     $this->result = new ScalarResult();
     $this->reset($dest, $destKey);
-    $this->throw = $defaultThrow ?? true;
+    $this->throw = $throw ?? true;
   }
 
   function isScalar(?ScalarWrapper &$scalar=null): bool { $scalar = $this; return true; }
@@ -137,19 +138,6 @@ class ScalarWrapper extends Wrapper {
     }
   }
 
-  function _extract(AnalyzerContext $context): bool {
-    return $context->type->extract($context->dest);
-  }
-
-  function _parse(AnalyzerContext $context): bool {
-    try {
-      $context->dest = $context->type->parse($context->dest);
-      return true;
-    } catch (ValueException $e) {
-      return false;
-    }
-  }
-
   function analyzeExtractParse(): int {
     $schema = $this->schema;
     $input = $this->input;
@@ -164,42 +152,41 @@ class ScalarWrapper extends Wrapper {
     else $what = $this->_analyze($context);
     if ($what !== ref_analyze::STRING) return $what;
 
-    /** @var func $extractorFunc */
-    $extractorFunc = $schema->extractorFunc;
-    if ($extractorFunc !== null) $valid = $extractorFunc->invoke([$context]);
-    else $valid = $this->_extract($context);
-    if (!$valid) return $result->setInvalid($context->orig, $schema);
-    if ($context->type->isNull($context->dest)) return $result->setNull($schema);
-    $extracted = $context->dest;
-
-    /** @var func $parserFunc */
-    $parserFunc = $schema->parserFunc;
-    if ($parserFunc !== null) $valid = $parserFunc->invoke([$context]);
-    else $valid = $this->_parse($context);
-    if ($valid) {
-      $normalized = $context->dest === $context->orig;
-      if ($normalized) {
-        $input->set($context->dest, $destKey);
-        return $result->setNormalized();
-      } else {
-        $input->set($extracted, $destKey);
-        return $result->setValid();
-      }
+    $dest = $context->dest;
+    try {
+      /** @var func $extractorFunc */
+      $extractorFunc = $schema->extractorFunc;
+      if ($extractorFunc !== null) $extracted = $extractorFunc->invoke([$dest, $context]);
+      else $extracted = $context->type->extract($dest);
+      $context->dest = $extracted;
+    } catch (ValueException $e) {
+      return $result->setInvalid($context->orig, $schema, $e);
+    }
+    if ($context->type->isNull($extracted)) return $result->setNull($schema);
+
+    try {
+      /** @var func $parserFunc */
+      $parserFunc = $schema->parserFunc;
+      if ($parserFunc !== null) $parsed = $parserFunc->invoke([$extracted, $context]);
+      else $parsed = $context->type->parse($extracted);
+      $context->dest = $parsed;
+    } catch (ValueException $e) {
+      return $result->setInvalid($context->orig, $schema, $e);
+    }
+
+    $normalized = $parsed === $context->orig;
+    if ($normalized) {
+      $input->set($parsed, $destKey);
+      return $result->setNormalized();
+    } else {
+      $input->set($extracted, $destKey);
+      return $result->setValid($parsed);
     }
-    return $result->setInvalid($context->orig, $schema);
   }
 
   function verifix(?bool $throw=null): bool {
-    $schema = $this->schema;
-    $input = $this->input;
-    $destKey = $this->destKey;
     $result = $this->result;
-    $context = new AnalyzerContext($schema, $this, $input, $destKey, $result);
-    /** @var func $normalizerFunc */
-    $normalizerFunc = $schema->normalizerFunc;
-    if ($normalizerFunc !== null) return $normalizerFunc->invoke([$context]);
-
-    if ($throw === null) $throw = $this->throw;
+    $destKey = $this->destKey;
     $verifix = false;
     $modified = false;
     if ($result->resultAvailable) {
@@ -208,18 +195,37 @@ class ScalarWrapper extends Wrapper {
         # valeur assimilée à null
         $this->input->set(null, $destKey);
       } elseif ($result->valid && !$result->normalized) {
-        # normaliser la valeur
-        $verifix = true;
+        $normalizedValue = $result->normalizedValue;
+        if ($normalizedValue !== null) {
+          # la valeur normalisée est disponible
+          $this->input->set($normalizedValue);
+          $result->normalizedValue = null;
+          $modified = true;
+        } else {
+          # normaliser la valeur
+          $verifix = true;
+        }
       }
     } else {
       $verifix = true;
     }
+
     if ($verifix) {
       $value = $this->input->get($destKey);
-      $modified = $this->type->verifix($value, $result, $this->schema);
+      $schema = $this->schema;
+      /** @var func $normalizerFunc */
+      $normalizerFunc = $schema->normalizerFunc;
+      if ($normalizerFunc !== null) {
+        $context = new AnalyzerContext($schema, $this, $this->input, $destKey, $result);
+        $orig = $value;
+        $value = $normalizerFunc->invoke([$orig, $context]);
+        $modified = $value !== $orig;
+      } else {
+        $modified = $this->type->verifix($value, $result, $this->schema);
+      }
       if ($result->valid) $this->input->set($value, $destKey);
     }
-    if (!$result->valid) $result->throw($throw);
+    if (!$result->valid) $result->throw($throw ?? $this->throw);
     return $modified;
   }
 
diff --git a/src/schema/types/IType.php b/src/schema/types/IType.php
index 5fcbda4..f0e564f 100644
--- a/src/schema/types/IType.php
+++ b/src/schema/types/IType.php
@@ -24,8 +24,12 @@ interface IType {
    */
   function isValid($value, ?bool &$normalized=null): bool;
 
-  /** extraire de la chaine la valeur à analyser */
-  function extract(string &$value): bool;
+  /**
+   * extraire de la chaine la valeur à analyser
+   *
+   * @throws ValueException en cas d'erreur d'analyse
+   */
+  function extract(string $value): string;
 
   /**
    * analyser la chaine et retourner la valeur "convertie"
diff --git a/src/schema/types/_tsimple.php b/src/schema/types/_tsimple.php
index c6d213c..91ded5d 100644
--- a/src/schema/types/_tsimple.php
+++ b/src/schema/types/_tsimple.php
@@ -22,7 +22,7 @@ abstract class _tsimple implements IType {
     return $value === null || $value === "";
   }
 
-  function extract(string &$value): bool {
-    return true;
+  function extract(string $value): string {
+    return $value;
   }
 }
diff --git a/src/schema/types/_tstring.php b/src/schema/types/_tstring.php
index d4928ff..782f2e6 100644
--- a/src/schema/types/_tstring.php
+++ b/src/schema/types/_tstring.php
@@ -18,9 +18,9 @@ abstract class _tstring extends _tsimple {
     return $params;
   }
 
-  function extract(string &$value): bool {
+  function extract(string $value): string {
     if ($this->params["trim"] ?? static::TRIM) $value = trim($value);
     if ($this->params["norm_nl"] ?? static::NORM_NL) $value = str::norm_nl($value);
-    return true;
+    return $value;
   }
 }
diff --git a/src/schema/types/tbool.php b/src/schema/types/tbool.php
index f89a01a..8e85a01 100644
--- a/src/schema/types/tbool.php
+++ b/src/schema/types/tbool.php
@@ -60,9 +60,8 @@ class tbool extends _tformatable {
     return is_scalar($value);
   }
 
-  function extract(string &$value): bool {
-    $value = trim($value);
-    return true;
+  function extract(string $value): string {
+    return trim($value);
   }
 
   function parse(string $value) {
diff --git a/src/schema/types/tfloat.php b/src/schema/types/tfloat.php
index 50668ac..47f3956 100644
--- a/src/schema/types/tfloat.php
+++ b/src/schema/types/tfloat.php
@@ -21,9 +21,8 @@ class tfloat extends _tformatable {
     return is_scalar($value);
   }
 
-  function extract(string &$value): bool {
-    $value = trim($value);
-    return true;
+  function extract(string $value): string {
+    return trim($value);
   }
 
   function parse(string $value) {
diff --git a/src/schema/types/tint.php b/src/schema/types/tint.php
index 395d5b7..51dbeec 100644
--- a/src/schema/types/tint.php
+++ b/src/schema/types/tint.php
@@ -23,9 +23,8 @@ class tint extends _tformatable {
     return is_scalar($value);
   }
 
-  function extract(string &$value): bool {
-    $value = trim($value);
-    return true;
+  function extract(string $value): string {
+    return trim($value);
   }
 
   function parse(string $value) {
diff --git a/tests/wip/schema/_scalar/ScalarValueTest.php b/tests/wip/schema/_scalar/ScalarValueTest.php
index 60d2f36..1fb9184 100644
--- a/tests/wip/schema/_scalar/ScalarValueTest.php
+++ b/tests/wip/schema/_scalar/ScalarValueTest.php
@@ -1,7 +1,6 @@
 <?php
 namespace nur\sery\wip\schema\_scalar;
 
-use Exception;
 use nulib\tests\TestCase;
 use nulib\ValueException;
 use nur\sery\wip\schema\input\Input;
@@ -34,6 +33,9 @@ class ScalarValueTest extends TestCase {
   function testRawstring() {
     $schema = new ScalarSchema("rawstring");
 
+    $this->checkVerifix($schema, false, false, null, true, false, true, true);
+    $this->checkVerifix($schema, false, true, null, true, false, true, true);
+
     $this->checkVerifix($schema, null, false, null, true, true, false, false);
     $this->checkException($schema, null, true, ValueException::class);
 
@@ -49,9 +51,6 @@ class ScalarValueTest extends TestCase {
     $this->checkVerifix($schema, "  text  ", false, "  text  ", true, true, true, true);
     $this->checkVerifix($schema, "  text  ", true, "  text  ", true, true, true, true);
 
-    $this->checkVerifix($schema, false, false, null, true, false, true, true);
-    $this->checkVerifix($schema, false, true, null, true, false, true, true);
-
     $this->checkVerifix($schema, true, false, true, true, true, true, false);
     $this->checkVerifix($schema, true, true, "1", true, true, true, false);
 
@@ -95,6 +94,9 @@ class ScalarValueTest extends TestCase {
   function testString() {
     $schema = new ScalarSchema("string");
 
+    $this->checkVerifix($schema, false, false, null, true, false, true, true);
+    $this->checkVerifix($schema, false, true, null, true, false, true, true);
+
     $this->checkVerifix($schema, null, false, null, true, true, false, false);
     $this->checkException($schema, null, true, ValueException::class);
 
@@ -102,16 +104,13 @@ class ScalarValueTest extends TestCase {
     $this->checkVerifix($schema, "", true, "", true, true, true, true);
 
     $this->checkVerifix($schema, "   ", false, "", true, true, true, false);
-    $this->checkVerifix($schema, "   ", true, "", true, true, true, true);
+    $this->checkVerifix($schema, "   ", true, "", true, true, true, false);
 
     $this->checkVerifix($schema, "text", false, "text", true, true, true, true);
     $this->checkVerifix($schema, "text", true, "text", true, true, true, true);
 
     $this->checkVerifix($schema, "  text  ", false, "text", true, true, true, false);
-    $this->checkVerifix($schema, "  text  ", true, "text", true, true, true, true);
-
-    $this->checkVerifix($schema, false, false, null, true, false, true, true);
-    $this->checkVerifix($schema, false, true, null, true, false, true, true);
+    $this->checkVerifix($schema, "  text  ", true, "text", true, true, true, false);
 
     $this->checkVerifix($schema, true, false, true, true, true, true, false);
     $this->checkVerifix($schema, true, true, "1", true, true, true, false);
@@ -133,11 +132,32 @@ class ScalarValueTest extends TestCase {
 
     $this->checkVerifix($schema, false, false, null, true, false, false, false);
     $this->checkException($schema, false, true, ValueException::class);
+
+    ## Tester allow_empty === false
+    $inputParams = ["allow_empty" => false];
+    $schema = new ScalarSchema("string");
+
+    $this->checkVerifix($schema, null, false, null, true, true, false, false, $inputParams);
+    $this->checkException($schema, null, true, ValueException::class, $inputParams);
+
+    $this->checkVerifix($schema, "", false, null, true, false, true, true, $inputParams);
+    $this->checkVerifix($schema, "", true, null, true, false, true, true, $inputParams);
+
+    $schema = new ScalarSchema("?string");
+
+    $this->checkVerifix($schema, null, false, null, true, true, true, true, $inputParams);
+    $this->checkVerifix($schema, null, true, null, true, true, true, true, $inputParams);
+
+    $this->checkVerifix($schema, "", false, null, true, false, true, true, $inputParams);
+    $this->checkVerifix($schema, "", true, null, true, false, true, true, $inputParams);
   }
 
   function testInt() {
     $schema = new ScalarSchema("int");
 
+    $this->checkVerifix($schema, false, false, null, true, false, true, true);
+    $this->checkVerifix($schema, false, true, null, true, false, true, true);
+
     $this->checkVerifix($schema, null, false, null, true, true, false, false);
     $this->checkException($schema, null, true, ValueException::class);
 
@@ -165,9 +185,6 @@ class ScalarValueTest extends TestCase {
     $this->checkVerifix($schema, "text", false, "text", true, true, false, false);
     $this->checkException($schema, "text", true, ValueException::class);
 
-    $this->checkVerifix($schema, false, false, null, true, false, true, true);
-    $this->checkVerifix($schema, false, true, null, true, false, true, true);
-
     $this->checkVerifix($schema, true, false, true, true, true, true, false);
     $this->checkVerifix($schema, true, true, 1, true, true, true, false);
 
@@ -185,5 +202,23 @@ class ScalarValueTest extends TestCase {
 
     $this->checkVerifix($schema, false, false, null, true, false, false, false);
     $this->checkException($schema, false, true, ValueException::class);
+
+    ## Tester allow_empty === false
+    $inputParams = ["allow_empty" => false];
+    $schema = new ScalarSchema("int");
+
+    $this->checkVerifix($schema, null, false, null, true, true, false, false, $inputParams);
+    $this->checkException($schema, null, true, ValueException::class, $inputParams);
+
+    $this->checkVerifix($schema, "", false, null, true, false, true, true, $inputParams);
+    $this->checkVerifix($schema, "", true, null, true, false, true, true, $inputParams);
+
+    $schema = new ScalarSchema("?int");
+
+    $this->checkVerifix($schema, null, false, null, true, true, true, true, $inputParams);
+    $this->checkVerifix($schema, null, true, null, true, true, true, true, $inputParams);
+
+    $this->checkVerifix($schema, "", false, null, true, false, true, true, $inputParams);
+    $this->checkVerifix($schema, "", true, null, true, false, true, true, $inputParams);
   }
 }