diff --git a/.gitignore b/.gitignore
index 4802f20..a5c71d3 100644
--- a/.gitignore
+++ b/.gitignore
@@ -3,5 +3,4 @@
 *.pyc
 *.mo
 *.swp
-version.in
 build/
diff --git a/MANIFEST.in b/MANIFEST.in
new file mode 100644
index 0000000..2835134
--- /dev/null
+++ b/MANIFEST.in
@@ -0,0 +1,8 @@
+# Include the README
+include *.rst
+
+# Include the license file
+include LICENSE.txt
+
+# Include the data files
+recursive-include tiramisu *.py *.mo
diff --git a/Makefile b/Makefile
index 0755b8f..57e8232 100644
--- a/Makefile
+++ b/Makefile
@@ -10,7 +10,7 @@ INSTALL_DATA    := install -m 644
 INSTALL_PROGRAM := install -m 755
 INSTALL_DIR     := install -m 755 -d
 
-TRADUC_DIR       = translations
+TRADUC_DIR       = tiramisu/locale
 TRADUC_DEST	 = $(DESTDIR)/usr/share/locale
 
 PYTHON_OPTS      =
@@ -26,7 +26,7 @@ define gettext
     else \
 	    P="pygettext.py" ; \
     fi ; \
-	$$P -p translations/ -o $(PACKAGE).pot `find $(PACKAGE)/ -name "*.py"`
+	$$P -p $(TRADUC_DIR)/ -o $(PACKAGE).pot `find $(PACKAGE)/ -name "*.py"`
 endef
 
 # Build translation files
@@ -69,12 +69,12 @@ build-pot:
 build-lang:
 	$(call build_translation, $(TRADUC_DIR))
 
-install-lang:
-	$(INSTALL_DIR) $(TRADUC_DEST)
-	$(call install_translation, $(TRADUC_DIR))
+# install-lang:
+# 	$(INSTALL_DIR) $(TRADUC_DEST)
+# 	$(call install_translation, $(TRADUC_DIR))
 
-install: install-lang
-	python setup.py install --no-compile $(PYTHON_OPTS)
+install: # install-lang
+	python3 setup.py install --no-compile $(PYTHON_OPTS)
 
 dist:
 	git archive --format=tar --prefix $(PACKAGE)-$(VERSION)/ HEAD | gzip -9 > $(PACKAGE)-$(VERSION).tar.gz
diff --git a/VERSION b/VERSION
deleted file mode 100644
index 1f7391f..0000000
--- a/VERSION
+++ /dev/null
@@ -1 +0,0 @@
-master
diff --git a/pyproject.toml b/pyproject.toml
new file mode 100644
index 0000000..95fdaf2
--- /dev/null
+++ b/pyproject.toml
@@ -0,0 +1,17 @@
+[build-system]
+requires = ["flit"]
+build-backend = "flit.buildapi"
+
+[tool.flit.metadata]
+module = "tiramisu"
+author = "Emmanuel Garette"
+author-email = "gnunux@gnunux.info"
+home-page = "https://framagit.org/tiramisu/tiramisu"
+classifiers = [
+	"License :: OSI Approved :: GNU Library or Lesser General Public License (LGPL)",
+        "Programming Language :: Python :: 3",
+	"Natural Language :: English",
+        "Natural Language :: French",
+        "Operating System :: OS Independent",
+]
+requires-python = ">=3.5"
diff --git a/setup.py b/setup.py
index 0374778..84c557d 100644
--- a/setup.py
+++ b/setup.py
@@ -1,57 +1,28 @@
 #!/usr/bin/env python
 # -*- coding: utf-8 -*-
-from distutils.core import setup
+from setuptools import setup, find_packages
 from os.path import dirname, abspath, join, normpath, isdir
 from os import listdir
 import os
+from tiramisu import __version__
 
 
-package_name = os.environ.get('PACKAGE_DST', 'tiramisu')
-
-def fetch_version():
-    """Get version from version.in"""
-    return open('VERSION', 'r').readline().strip()
-
-
-def return_files(component):
-    here = dirname(abspath(__file__))
-    path = normpath(join(here, 'tiramisu', component))
-    dir_content = [content for content in listdir(path)
-                   if not content == '__pycache__']
-    paths = filter(isdir, [join(path, content)
-                      for content in dir_content])
-    lst = ['.'.join(path.split('/')[-3:]) for path in paths]
-    #lst = [package_name + '.' + '.'.join(path.split('/')[-2:]) for path in paths]
-    return lst
-
-
-packages = [package_name, package_name + '.storage', package_name + '.option']
-packages.extend(return_files('storage'))
-packages.extend(return_files('option'))
-
-if package_name != 'tiramisu':
-    package_dir = {package_name: 'tiramisu'}
-else:
-    package_dir = {}
+PACKAGE_NAME = os.environ.get('PACKAGE_DST', 'tiramisu')
 
 setup(
+    version=__version__,
     author="Tiramisu's team",
-    author_email='contact@cadoles.com',
-    name=package_name,
-    version=fetch_version(),
+    author_email='gnunux@gnunux.info',
+    name=PACKAGE_NAME,
     description='an options controller tool',
-    url='http://tiramisu.labs.libre-entreprise.org/',
+    url='https://framagit.org/tiramisu/tiramisu',
+    license='GNU Library or Lesser General Public License (LGPL)',
     classifiers=[
-        "Programming Language :: Python",
-        "Programming Language :: Python :: 2",
         "Programming Language :: Python :: 3",
-        "Development Status :: 4 - Beta",
-        "Environment :: Other Environment",
-        "Intended Audience :: Developers",
         "License :: OSI Approved :: GNU Library or Lesser General Public License (LGPL)",
         "Operating System :: OS Independent",
-        "Topic :: Software Development :: Libraries :: Python Modules",
-        "Topic :: Text Processing :: Linguistic"
+	    "Natural Language :: English",
+        "Natural Language :: French",
     ],
     long_description="""\
 An options controller tool
@@ -67,8 +38,8 @@ Tiramisu is an options handler and an options controller, wich aims at
 producing flexible and fast options access.
 
 
-This version requires Python 2.6 or later.
+This version requires Python 3.5 or later.
 """,
-    packages=packages,
-    package_dir=package_dir
+    include_package_data=True,
+    packages=find_packages(include=['tiramisu'])
 )
diff --git a/tiramisu/__init__.py b/tiramisu/__init__.py
index db7fad8..bc7a6f1 100644
--- a/tiramisu/__init__.py
+++ b/tiramisu/__init__.py
@@ -12,6 +12,8 @@
 #
 # You should have received a copy of the GNU Lesser General Public License
 # along with this program.  If not, see <http://www.gnu.org/licenses/>.
+"""Configuration management library written in python
+"""
 from .function import Params, ParamOption, ParamValue, ParamContext, \
                       tiramisu_copy, calc_value
 from .option import *
@@ -43,3 +45,4 @@ allfuncs.extend(all_options)
 del(all_options)
 __all__ = tuple(allfuncs)
 del(allfuncs)
+__version__ = "3.0rc5"
diff --git a/tiramisu/i18n.py b/tiramisu/i18n.py
index 0a7601d..c872da7 100644
--- a/tiramisu/i18n.py
+++ b/tiramisu/i18n.py
@@ -18,34 +18,43 @@
 # the rough gus of pypy: pypy: http://codespeak.net/svn/pypy/dist/pypy/config/
 # the whole pypy projet is under MIT licence
 "internationalisation utilities"
-import gettext
-import os
-import sys
-import locale
+from gettext import translation, NullTranslations
+from platform import system
+from pkg_resources import resource_filename
+from .log import log
 
-# Application Name
-APP_NAME = 'tiramisu'
 
-# Traduction dir
-APP_DIR = os.path.join(sys.prefix, 'share')
-LOCALE_DIR = os.path.join(APP_DIR, 'locale')
+def get_translation() -> str:
+    """Sets the user locale as langage
+    The default is set to english
+    """
+    # Application name (without .i18n)
+    app_name = __name__[:-5]
+    translations_path = resource_filename(app_name, 'locale')
 
-# Default Lanugage
-DEFAULT_LANG = os.environ.get('LANG', '').split(':')
-DEFAULT_LANG += ['en_US']
+    if 'Windows' in system():
+        import ctypes
+        from locale import windows_locale
+        default_locale = windows_locale[ctypes.windll.kernel32.GetUserDefaultUILanguage()]
+    else:
+        from locale import getdefaultlocale
+        default_locale = getdefaultlocale()
+    if default_locale and isinstance(default_locale, tuple):
+        user_locale = default_locale[0][:2]
+    elif default_locale:
+        user_locale = default_locale[:2]
+    else:
+        user_locale = 'en'
+    try:
+        trans = translation(domain=app_name,
+                            localedir=translations_path,
+                            languages=[user_locale],
+                            codeset='UTF-8')
+    except FileNotFoundError:
+        log.debug('cannot found translation file for langage {} in localedir {}'.format(user_locale,
+                                                                                        translations_path))
+        trans = NullTranslations()
+    return trans.gettext
 
-languages = []
-lc, encoding = locale.getdefaultlocale()
-if lc:
-    languages = [lc]
 
-languages += DEFAULT_LANG
-mo_location = LOCALE_DIR
-
-gettext.find(APP_NAME, mo_location)
-gettext.textdomain(APP_NAME)
-gettext.bind_textdomain_codeset(APP_NAME, "UTF-8")
-
-t = gettext.translation(APP_NAME, fallback=True)
-
-_ = t.gettext
+_ = get_translation()
diff --git a/translations/fr/tiramisu.po b/tiramisu/locale/fr/LC_MESSAGES/tiramisu.po
similarity index 100%
rename from translations/fr/tiramisu.po
rename to tiramisu/locale/fr/LC_MESSAGES/tiramisu.po
diff --git a/translations/tiramisu.pot b/tiramisu/locale/tiramisu.pot
similarity index 76%
rename from translations/tiramisu.pot
rename to tiramisu/locale/tiramisu.pot
index b3fb9b8..e77bb93 100644
--- a/translations/tiramisu.pot
+++ b/tiramisu/locale/tiramisu.pot
@@ -5,7 +5,7 @@
 msgid ""
 msgstr ""
 "Project-Id-Version: PACKAGE VERSION\n"
-"POT-Creation-Date: 2019-03-05 08:46+CET\n"
+"POT-Creation-Date: 2019-04-07 10:39+CEST\n"
 "PO-Revision-Date: YEAR-MO-DA HO:MI+ZONE\n"
 "Last-Translator: FULL NAME <EMAIL@ADDRESS>\n"
 "Language-Team: LANGUAGE <LL@li.org>\n"
@@ -55,31 +55,31 @@ msgstr ""
 msgid "cannot add this property: \"{0}\""
 msgstr ""
 
-#: tiramisu/api.py:503 tiramisu/config.py:252
+#: tiramisu/api.py:504 tiramisu/config.py:252
 msgid "can't delete a SymLinkOption"
 msgstr ""
 
-#: tiramisu/api.py:636 tiramisu/api.py:1322
+#: tiramisu/api.py:637 tiramisu/api.py:1326
 msgid "please specify a valid sub function ({})"
 msgstr ""
 
-#: tiramisu/api.py:699 tiramisu/api.py:1145
+#: tiramisu/api.py:700 tiramisu/api.py:1146
 msgid "unknown list type {}"
 msgstr ""
 
-#: tiramisu/api.py:701 tiramisu/api.py:1147
+#: tiramisu/api.py:702 tiramisu/api.py:1148
 msgid "unknown group_type: {0}"
 msgstr ""
 
-#: tiramisu/api.py:974
+#: tiramisu/api.py:975
 msgid "properties must be a set"
 msgstr ""
 
-#: tiramisu/api.py:980 tiramisu/api.py:1002
+#: tiramisu/api.py:981 tiramisu/api.py:1003
 msgid "unknown when {} (must be in append or remove)"
 msgstr ""
 
-#: tiramisu/api.py:992 tiramisu/api.py:1014 tiramisu/config.py:1227
+#: tiramisu/api.py:993 tiramisu/api.py:1015 tiramisu/config.py:1249
 msgid "unknown type {}"
 msgstr ""
 
@@ -171,7 +171,7 @@ msgstr ""
 msgid "unknown config \"{}\""
 msgstr ""
 
-#: tiramisu/config.py:987 tiramisu/config.py:1202
+#: tiramisu/config.py:987 tiramisu/config.py:1224
 msgid "{}config's children should be config, not {}"
 msgstr ""
 
@@ -191,26 +191,34 @@ msgstr ""
 msgid "force_default and force_dont_change_value cannot be set together"
 msgstr ""
 
-#: tiramisu/config.py:1189
-msgid "MetaConfig with optiondescription must have string has child, not {}"
+#: tiramisu/config.py:1176
+msgid "config is already in a metaconfig"
 msgstr ""
 
-#: tiramisu/config.py:1208
-msgid "child must be a Config or MetaConfig"
-msgstr ""
-
-#: tiramisu/config.py:1212
-msgid "all config in metaconfig must have the same optiondescription"
-msgstr ""
-
-#: tiramisu/config.py:1225
+#: tiramisu/config.py:1178 tiramisu/config.py:1247
 msgid "config name must be uniq in groupconfig for {0}"
 msgstr ""
 
-#: tiramisu/config.py:1250
+#: tiramisu/config.py:1192
 msgid "cannot find the config {}"
 msgstr ""
 
+#: tiramisu/config.py:1211
+msgid "MetaConfig with optiondescription must have string has child, not {}"
+msgstr ""
+
+#: tiramisu/config.py:1230
+msgid "child must be a Config or MetaConfig"
+msgstr ""
+
+#: tiramisu/config.py:1234
+msgid "all config in metaconfig must have the same optiondescription"
+msgstr ""
+
+#: tiramisu/config.py:1272
+msgid "metaconfig must have the same optiondescription"
+msgstr ""
+
 #: tiramisu/error.py:24
 msgid "and"
 msgstr ""
@@ -223,11 +231,11 @@ msgstr ""
 msgid " {} "
 msgstr ""
 
-#: tiramisu/error.py:103 tiramisu/setting.py:563
+#: tiramisu/error.py:103 tiramisu/setting.py:579
 msgid "property"
 msgstr ""
 
-#: tiramisu/error.py:105 tiramisu/setting.py:565
+#: tiramisu/error.py:105 tiramisu/setting.py:581
 msgid "properties"
 msgstr ""
 
@@ -239,38 +247,42 @@ msgstr ""
 msgid "cannot access to {0} \"{1}\" because has {2} {3}"
 msgstr ""
 
-#: tiramisu/error.py:185
+#: tiramisu/error.py:189
 msgid "invalid value"
 msgstr ""
 
-#: tiramisu/error.py:190
+#: tiramisu/error.py:194
 msgid "attention, \"{0}\" could be an invalid {1} for \"{2}\""
 msgstr ""
 
-#: tiramisu/error.py:194 tiramisu/error.py:198
+#: tiramisu/error.py:198 tiramisu/error.py:202
 msgid "\"{0}\" is an invalid {1} for \"{2}\""
 msgstr ""
 
-#: tiramisu/function.py:31
+#: tiramisu/function.py:34
 msgid "args in params must be a tuple"
 msgstr ""
 
-#: tiramisu/function.py:34 tiramisu/function.py:39
+#: tiramisu/function.py:37 tiramisu/function.py:42
 msgid "arg in params must be a Param"
 msgstr ""
 
-#: tiramisu/function.py:36
+#: tiramisu/function.py:39
 msgid "kwargs in params must be a dict"
 msgstr ""
 
-#: tiramisu/function.py:52
+#: tiramisu/function.py:58
 msgid "paramoption needs an option not {}"
 msgstr ""
 
-#: tiramisu/function.py:58
+#: tiramisu/function.py:64
 msgid "param must have a boolean not a {} for notraisepropertyerror"
 msgstr ""
 
+#: tiramisu/function.py:271
+msgid "unexpected {} condition_operator in calc_value"
+msgstr ""
+
 #: tiramisu/option/baseoption.py:75 tiramisu/option/symlinkoption.py:33
 msgid "\"{0}\" is an invalid name for an option"
 msgstr ""
@@ -299,124 +311,124 @@ msgstr ""
 msgid "missing those arguments \"{}\" in function \"{}\" for \"{}\""
 msgstr ""
 
-#: tiramisu/option/baseoption.py:257
+#: tiramisu/option/baseoption.py:258
 msgid "params defined for a callback function but no callback defined yet for option \"{0}\""
 msgstr ""
 
-#: tiramisu/option/baseoption.py:349 tiramisu/storage/dictionary/value.py:275
+#: tiramisu/option/baseoption.py:350 tiramisu/storage/dictionary/value.py:275
 #: tiramisu/storage/sqlite3/value.py:201
 msgid "information's item not found: {0}"
 msgstr ""
 
-#: tiramisu/option/baseoption.py:362
+#: tiramisu/option/baseoption.py:363
 msgid "'{0}' ({1}) object attribute '{2}' is read-only"
 msgstr ""
 
-#: tiramisu/option/baseoption.py:393
+#: tiramisu/option/baseoption.py:394
 msgid "\"{}\" ({}) object attribute \"{}\" is read-only"
 msgstr ""
 
-#: tiramisu/option/baseoption.py:403
+#: tiramisu/option/baseoption.py:404
 msgid "\"{}\" not part of any Config"
 msgstr ""
 
-#: tiramisu/option/baseoption.py:450
+#: tiramisu/option/baseoption.py:453
 msgid "malformed requirements must be an option in option {0}"
 msgstr ""
 
-#: tiramisu/option/baseoption.py:453
+#: tiramisu/option/baseoption.py:456
 msgid "malformed requirements multi option must not set as requires of non multi option {0}"
 msgstr ""
 
-#: tiramisu/option/baseoption.py:486
+#: tiramisu/option/baseoption.py:495
 msgid "malformed requirements expected must have option and value for option {0}"
 msgstr ""
 
-#: tiramisu/option/baseoption.py:493 tiramisu/option/baseoption.py:509
+#: tiramisu/option/baseoption.py:502 tiramisu/option/baseoption.py:518
 msgid "malformed requirements expected value must be valid for option {0}: {1}"
 msgstr ""
 
-#: tiramisu/option/baseoption.py:523
+#: tiramisu/option/baseoption.py:532
 msgid "malformed requirements for option: {0} action cannot be force_store_value"
 msgstr ""
 
-#: tiramisu/option/baseoption.py:531
+#: tiramisu/option/baseoption.py:540
 msgid "malformed requirements for option: {0} inverse must be boolean"
 msgstr ""
 
-#: tiramisu/option/baseoption.py:538
+#: tiramisu/option/baseoption.py:547
 msgid "malformed requirements for option: {0} transitive must be boolean"
 msgstr ""
 
-#: tiramisu/option/baseoption.py:545
+#: tiramisu/option/baseoption.py:554
 msgid "malformed requirements for option: {0} same_action must be boolean"
 msgstr ""
 
-#: tiramisu/option/baseoption.py:552
+#: tiramisu/option/baseoption.py:561
 msgid "malformed requirements for option: \"{0}\" operator must be \"or\" or \"and\""
 msgstr ""
 
-#: tiramisu/option/baseoption.py:564
+#: tiramisu/option/baseoption.py:574
 msgid "malformed requirements type for option: {0}, must be a dict"
 msgstr ""
 
-#: tiramisu/option/baseoption.py:570
+#: tiramisu/option/baseoption.py:580
 msgid "malformed requirements for option: {0} unknown keys {1}, must only {2}"
 msgstr ""
 
-#: tiramisu/option/baseoption.py:579
+#: tiramisu/option/baseoption.py:592
 msgid "malformed requirements for option: {0} require must have option, expected and action keys"
 msgstr ""
 
-#: tiramisu/option/booloption.py:30
+#: tiramisu/option/booloption.py:31
 msgid "boolean"
 msgstr ""
 
-#: tiramisu/option/broadcastoption.py:31
+#: tiramisu/option/broadcastoption.py:32
 msgid "broadcast address"
 msgstr ""
 
-#: tiramisu/option/broadcastoption.py:38 tiramisu/option/dateoption.py:37
-#: tiramisu/option/domainnameoption.py:113 tiramisu/option/ipoption.py:77
-#: tiramisu/option/netmaskoption.py:41 tiramisu/option/networkoption.py:67
-#: tiramisu/option/passwordoption.py:38 tiramisu/option/portoption.py:106
-#: tiramisu/option/urloption.py:40
+#: tiramisu/option/broadcastoption.py:39 tiramisu/option/dateoption.py:38
+#: tiramisu/option/domainnameoption.py:118 tiramisu/option/ipoption.py:83
+#: tiramisu/option/netmaskoption.py:42 tiramisu/option/networkoption.py:68
+#: tiramisu/option/passwordoption.py:39 tiramisu/option/portoption.py:107
+#: tiramisu/option/urloption.py:41
 msgid "invalid string"
 msgstr ""
 
-#: tiramisu/option/broadcastoption.py:56
+#: tiramisu/option/broadcastoption.py:57
 msgid "invalid len for vals"
 msgstr ""
 
-#: tiramisu/option/broadcastoption.py:61
+#: tiramisu/option/broadcastoption.py:62
 msgid "broadcast \"{4}\" invalid with network {0}/{1} (\"{2}\"/\"{3}\")"
 msgstr ""
 
-#: tiramisu/option/choiceoption.py:36
+#: tiramisu/option/choiceoption.py:37
 msgid "choice"
 msgstr ""
 
-#: tiramisu/option/choiceoption.py:65
+#: tiramisu/option/choiceoption.py:66
 msgid "values is not a function, so values_params must be None"
 msgstr ""
 
-#: tiramisu/option/choiceoption.py:67
+#: tiramisu/option/choiceoption.py:68
 msgid "values must be a tuple or a function for {0}"
 msgstr ""
 
-#: tiramisu/option/choiceoption.py:100
+#: tiramisu/option/choiceoption.py:101
 msgid "calculated values for {0} is not a list"
 msgstr ""
 
-#: tiramisu/option/choiceoption.py:113
+#: tiramisu/option/choiceoption.py:114
 msgid "only \"{0}\" is allowed"
 msgstr ""
 
-#: tiramisu/option/choiceoption.py:116
+#: tiramisu/option/choiceoption.py:117
 msgid "only \"{0}\" are allowed"
 msgstr ""
 
-#: tiramisu/option/dateoption.py:30
+#: tiramisu/option/dateoption.py:31
 msgid "date"
 msgstr ""
 
@@ -424,43 +436,43 @@ msgstr ""
 msgid "domain name"
 msgstr ""
 
-#: tiramisu/option/domainnameoption.py:58
+#: tiramisu/option/domainnameoption.py:59
 msgid "unknown type_ {0} for hostname"
 msgstr ""
 
-#: tiramisu/option/domainnameoption.py:61
+#: tiramisu/option/domainnameoption.py:62
 msgid "allow_ip must be a boolean"
 msgstr ""
 
-#: tiramisu/option/domainnameoption.py:63
+#: tiramisu/option/domainnameoption.py:64
 msgid "allow_without_dot must be a boolean"
 msgstr ""
 
-#: tiramisu/option/domainnameoption.py:107
+#: tiramisu/option/domainnameoption.py:112
 msgid "invalid length (min 1)"
 msgstr ""
 
-#: tiramisu/option/domainnameoption.py:109
+#: tiramisu/option/domainnameoption.py:114
 msgid "invalid length (max {0})"
 msgstr ""
 
-#: tiramisu/option/domainnameoption.py:121
+#: tiramisu/option/domainnameoption.py:125
 msgid "must not be an IP"
 msgstr ""
 
-#: tiramisu/option/domainnameoption.py:125
+#: tiramisu/option/domainnameoption.py:131
 msgid "must have dot"
 msgstr ""
 
-#: tiramisu/option/domainnameoption.py:127
+#: tiramisu/option/domainnameoption.py:133
 msgid "invalid length (max 255)"
 msgstr ""
 
-#: tiramisu/option/domainnameoption.py:135
+#: tiramisu/option/domainnameoption.py:141
 msgid "some characters are uppercase"
 msgstr ""
 
-#: tiramisu/option/domainnameoption.py:138
+#: tiramisu/option/domainnameoption.py:144
 msgid "some characters may cause problems"
 msgstr ""
 
@@ -488,63 +500,63 @@ msgstr ""
 msgid "DynOptionDescription callback return a list with multiple value \"{}\""
 msgstr ""
 
-#: tiramisu/option/emailoption.py:31
+#: tiramisu/option/emailoption.py:32
 msgid "email address"
 msgstr ""
 
-#: tiramisu/option/filenameoption.py:30
+#: tiramisu/option/filenameoption.py:31
 msgid "file name"
 msgstr ""
 
-#: tiramisu/option/floatoption.py:30
+#: tiramisu/option/floatoption.py:31
 msgid "float"
 msgstr ""
 
-#: tiramisu/option/intoption.py:30
+#: tiramisu/option/intoption.py:31
 msgid "integer"
 msgstr ""
 
-#: tiramisu/option/intoption.py:54
+#: tiramisu/option/intoption.py:55
 msgid "value must be greater than \"{0}\""
 msgstr ""
 
-#: tiramisu/option/intoption.py:57
+#: tiramisu/option/intoption.py:58
 msgid "value must be less than \"{0}\""
 msgstr ""
 
-#: tiramisu/option/ipoption.py:35
+#: tiramisu/option/ipoption.py:36
 msgid "IP"
 msgstr ""
 
-#: tiramisu/option/ipoption.py:83 tiramisu/option/networkoption.py:73
+#: tiramisu/option/ipoption.py:89 tiramisu/option/networkoption.py:74
 msgid "must use CIDR notation"
 msgstr ""
 
-#: tiramisu/option/ipoption.py:105
+#: tiramisu/option/ipoption.py:111
 msgid "shouldn't be reserved IP"
 msgstr ""
 
-#: tiramisu/option/ipoption.py:107
+#: tiramisu/option/ipoption.py:113
 msgid "mustn't be reserved IP"
 msgstr ""
 
-#: tiramisu/option/ipoption.py:111
+#: tiramisu/option/ipoption.py:117
 msgid "should be private IP"
 msgstr ""
 
-#: tiramisu/option/ipoption.py:113
+#: tiramisu/option/ipoption.py:119
 msgid "must be private IP"
 msgstr ""
 
-#: tiramisu/option/ipoption.py:141
+#: tiramisu/option/ipoption.py:147
 msgid "\"{0}\" is not in network \"{1}\" (\"{2}\")"
 msgstr ""
 
-#: tiramisu/option/ipoption.py:157
+#: tiramisu/option/ipoption.py:163
 msgid "ip_network needs an IP, a network and a netmask"
 msgstr ""
 
-#: tiramisu/option/ipoption.py:163
+#: tiramisu/option/ipoption.py:169
 msgid "\"{4}\" is not in network \"{0}\"/\"{1}\" (\"{2}\"/\"{3}\")"
 msgstr ""
 
@@ -580,51 +592,51 @@ msgstr ""
 msgid "malformed requirements option \"{0}\" must not be in follower for \"{1}\""
 msgstr ""
 
-#: tiramisu/option/netmaskoption.py:34
+#: tiramisu/option/netmaskoption.py:35
 msgid "netmask address"
 msgstr ""
 
-#: tiramisu/option/netmaskoption.py:59
+#: tiramisu/option/netmaskoption.py:60
 msgid "network_netmask needs a network and a netmask"
 msgstr ""
 
-#: tiramisu/option/netmaskoption.py:68
+#: tiramisu/option/netmaskoption.py:69
 msgid "with netmask \"{0}\" (\"{1}\")"
 msgstr ""
 
-#: tiramisu/option/netmaskoption.py:71
+#: tiramisu/option/netmaskoption.py:72
 msgid "with network \"{0}\" (\"{1}\")"
 msgstr ""
 
-#: tiramisu/option/netmaskoption.py:82
+#: tiramisu/option/netmaskoption.py:83
 msgid "ip_netmask needs an IP and a netmask"
 msgstr ""
 
-#: tiramisu/option/netmaskoption.py:90
+#: tiramisu/option/netmaskoption.py:91
 msgid "this is a network with netmask \"{0}\" (\"{1}\")"
 msgstr ""
 
-#: tiramisu/option/netmaskoption.py:94
+#: tiramisu/option/netmaskoption.py:95
 msgid "this is a broadcast with netmask \"{0}\" (\"{1}\")"
 msgstr ""
 
-#: tiramisu/option/netmaskoption.py:99
+#: tiramisu/option/netmaskoption.py:100
 msgid "IP \"{0}\" (\"{1}\") is the network"
 msgstr ""
 
-#: tiramisu/option/netmaskoption.py:103
+#: tiramisu/option/netmaskoption.py:104
 msgid "IP \"{0}\" (\"{1}\") is the broadcast"
 msgstr ""
 
-#: tiramisu/option/networkoption.py:31
+#: tiramisu/option/networkoption.py:32
 msgid "network address"
 msgstr ""
 
-#: tiramisu/option/networkoption.py:90
+#: tiramisu/option/networkoption.py:91
 msgid "shouldn't be reserved network"
 msgstr ""
 
-#: tiramisu/option/networkoption.py:92
+#: tiramisu/option/networkoption.py:93
 msgid "mustn't be reserved network"
 msgstr ""
 
@@ -652,79 +664,79 @@ msgstr ""
 msgid "invalid default_multi value \"{0}\" for option \"{1}\", must be a list for a submulti"
 msgstr ""
 
-#: tiramisu/option/option.py:255
+#: tiramisu/option/option.py:259
 msgid "invalid value \"{}\", this value is already in \"{}\""
 msgstr ""
 
-#: tiramisu/option/option.py:285
+#: tiramisu/option/option.py:289
 msgid "which must not be a list"
 msgstr ""
 
-#: tiramisu/option/option.py:319 tiramisu/option/option.py:328
+#: tiramisu/option/option.py:323 tiramisu/option/option.py:332
 msgid "which must be a list"
 msgstr ""
 
-#: tiramisu/option/option.py:333
+#: tiramisu/option/option.py:337
 msgid "which \"{}\" must be a list of list"
 msgstr ""
 
-#: tiramisu/option/option.py:375
+#: tiramisu/option/option.py:379
 msgid "default value not allowed if option \"{0}\" is calculated"
 msgstr ""
 
-#: tiramisu/option/option.py:423
+#: tiramisu/option/option.py:427
 msgid "'{0}' ({1}) cannot add consistency, option is read-only"
 msgstr ""
 
-#: tiramisu/option/option.py:431
+#: tiramisu/option/option.py:435
 msgid "consistency {0} not available for this option"
 msgstr ""
 
-#: tiramisu/option/option.py:438
+#: tiramisu/option/option.py:442
 msgid "unknown parameter {0} in consistency"
 msgstr ""
 
-#: tiramisu/option/option.py:550 tiramisu/option/option.py:555
+#: tiramisu/option/option.py:554 tiramisu/option/option.py:559
 msgid "cannot add consistency with submulti option"
 msgstr ""
 
-#: tiramisu/option/option.py:556
+#: tiramisu/option/option.py:560
 msgid "consistency must be set with an option, not {}"
 msgstr ""
 
-#: tiramisu/option/option.py:559 tiramisu/option/option.py:567
+#: tiramisu/option/option.py:563 tiramisu/option/option.py:571
 msgid "almost one option in consistency is in a dynoptiondescription but not all"
 msgstr ""
 
-#: tiramisu/option/option.py:563
+#: tiramisu/option/option.py:567
 msgid "option in consistency must be in same dynoptiondescription"
 msgstr ""
 
-#: tiramisu/option/option.py:570
+#: tiramisu/option/option.py:574
 msgid "cannot add consistency with itself"
 msgstr ""
 
-#: tiramisu/option/option.py:572
+#: tiramisu/option/option.py:576
 msgid "every options in consistency must be multi or none"
 msgstr ""
 
-#: tiramisu/option/option.py:612
+#: tiramisu/option/option.py:616
 msgid "unexpected length of \"{}\" in constency \"{}\", should be \"{}\""
 msgstr ""
 
-#: tiramisu/option/option.py:712
+#: tiramisu/option/option.py:716
 msgid "should be different from the value of \"{}\""
 msgstr ""
 
-#: tiramisu/option/option.py:714
+#: tiramisu/option/option.py:718
 msgid "must be different from the value of \"{}\""
 msgstr ""
 
-#: tiramisu/option/option.py:717
+#: tiramisu/option/option.py:721
 msgid "value for {} should be different"
 msgstr ""
 
-#: tiramisu/option/option.py:719
+#: tiramisu/option/option.py:723
 msgid "value for {} must be different"
 msgstr ""
 
@@ -741,7 +753,7 @@ msgstr ""
 msgid "the dynoption \"{0}\" cannot have \"force_store_value\" property"
 msgstr ""
 
-#: tiramisu/option/optiondescription.py:97 tiramisu/setting.py:643
+#: tiramisu/option/optiondescription.py:97 tiramisu/setting.py:665
 msgid "a leader ({0}) cannot have \"force_default_on_freeze\" or \"force_metaconfig_on_freeze\" property without \"frozen\""
 msgstr ""
 
@@ -797,35 +809,35 @@ msgstr ""
 msgid "group_type: {0} not allowed"
 msgstr ""
 
-#: tiramisu/option/passwordoption.py:31
+#: tiramisu/option/passwordoption.py:32
 msgid "password"
 msgstr ""
 
-#: tiramisu/option/portoption.py:43
+#: tiramisu/option/portoption.py:44
 msgid "port"
 msgstr ""
 
-#: tiramisu/option/portoption.py:80
+#: tiramisu/option/portoption.py:81
 msgid "inconsistency in allowed range"
 msgstr ""
 
-#: tiramisu/option/portoption.py:85
+#: tiramisu/option/portoption.py:86
 msgid "max value is empty"
 msgstr ""
 
-#: tiramisu/option/portoption.py:110
+#: tiramisu/option/portoption.py:111
 msgid "range must have two values only"
 msgstr ""
 
-#: tiramisu/option/portoption.py:112
+#: tiramisu/option/portoption.py:113
 msgid "first port in range must be smaller than the second one"
 msgstr ""
 
-#: tiramisu/option/portoption.py:122
+#: tiramisu/option/portoption.py:123
 msgid "must be an integer between {0} and {1}"
 msgstr ""
 
-#: tiramisu/option/stroption.py:32
+#: tiramisu/option/stroption.py:33
 msgid "string"
 msgstr ""
 
@@ -837,23 +849,23 @@ msgstr ""
 msgid "unknown option \"{0}\" in syndynoptiondescription \"{1}\""
 msgstr ""
 
-#: tiramisu/option/urloption.py:33
+#: tiramisu/option/urloption.py:34
 msgid "URL"
 msgstr ""
 
-#: tiramisu/option/urloption.py:43
+#: tiramisu/option/urloption.py:44
 msgid "must start with http:// or https://"
 msgstr ""
 
-#: tiramisu/option/urloption.py:61
+#: tiramisu/option/urloption.py:62
 msgid "port must be an between 0 and 65536"
 msgstr ""
 
-#: tiramisu/option/urloption.py:70
+#: tiramisu/option/urloption.py:71
 msgid "must ends with a valid resource name"
 msgstr ""
 
-#: tiramisu/option/usernameoption.py:31
+#: tiramisu/option/usernameoption.py:32
 msgid "username"
 msgstr ""
 
@@ -865,47 +877,55 @@ msgstr ""
 msgid "can't unbind {0}"
 msgstr ""
 
-#: tiramisu/setting.py:518
+#: tiramisu/setting.py:519
 msgid "malformed requirements imbrication detected for option: '{0}' with requirement on: '{1}'"
 msgstr ""
 
-#: tiramisu/setting.py:566
+#: tiramisu/setting.py:582
 msgid "cannot access to option \"{0}\" because required option \"{1}\" has {2} {3}"
 msgstr ""
 
-#: tiramisu/setting.py:590
+#: tiramisu/setting.py:608
+msgid "the calculated value is {0}"
+msgstr ""
+
+#: tiramisu/setting.py:610
+msgid "the calculated value is not {0}"
+msgstr ""
+
+#: tiramisu/setting.py:614
 msgid "the value of \"{0}\" is {1}"
 msgstr ""
 
-#: tiramisu/setting.py:592
+#: tiramisu/setting.py:616
 msgid "the value of \"{0}\" is not {1}"
 msgstr ""
 
-#: tiramisu/setting.py:633
+#: tiramisu/setting.py:655
 msgid "cannot set property {} for option \"{}\" this property is calculated"
 msgstr ""
 
-#: tiramisu/setting.py:638
+#: tiramisu/setting.py:660
 msgid "can't assign property to the symlinkoption \"{}\""
 msgstr ""
 
-#: tiramisu/setting.py:670
+#: tiramisu/setting.py:692
 msgid "permissive must be a frozenset"
 msgstr ""
 
-#: tiramisu/setting.py:674
+#: tiramisu/setting.py:696
 msgid "can't assign permissive to the symlinkoption \"{}\""
 msgstr ""
 
-#: tiramisu/setting.py:681
+#: tiramisu/setting.py:703
 msgid "cannot add those permissives: {0}"
 msgstr ""
 
-#: tiramisu/setting.py:698
+#: tiramisu/setting.py:720
 msgid "can't reset properties to the symlinkoption \"{}\""
 msgstr ""
 
-#: tiramisu/setting.py:713
+#: tiramisu/setting.py:735
 msgid "can't reset permissives to the symlinkoption \"{}\""
 msgstr ""
 
@@ -939,19 +959,19 @@ msgstr ""
 msgid "cannot change setting when connexion is already opened"
 msgstr ""
 
-#: tiramisu/value.py:424
+#: tiramisu/value.py:427
 msgid "can't set owner for the symlinkoption \"{}\""
 msgstr ""
 
-#: tiramisu/value.py:427 tiramisu/value.py:639
+#: tiramisu/value.py:430 tiramisu/value.py:642
 msgid "set owner \"{0}\" is forbidden"
 msgstr ""
 
-#: tiramisu/value.py:430
+#: tiramisu/value.py:433
 msgid "no value for {0} cannot change owner to {1}"
 msgstr ""
 
-#: tiramisu/value.py:508
+#: tiramisu/value.py:511
 msgid "index \"{}\" is higher than the length \"{}\" for option \"{}\""
 msgstr ""
 
diff --git a/tiramisu/storage/cache/__init__.py b/tiramisu/storage/cache/__init__.py
new file mode 100644
index 0000000..e69de29