for a multi mandatory, allow [] with allow_empty_list attribut

tiramisu/option/baseoption.py

@@ -99,7 +99,7 @@ class Base(StorageBase):
     def __init__(self, name, doc, default=None, default_multi=None,
                  requires=None, multi=False, callback=None,
                  callback_params=None, validator=None, validator_params=None,
-                 properties=None, warnings_only=False, extra=None):
+                 properties=None, warnings_only=False, extra=None, allow_empty_list=False):
         if not valid_name(name):  # pragma: optional cover
             raise ValueError(_("invalid name: {0} for option").format(name))
         if requires is not None:
@@ -134,7 +134,7 @@ class Base(StorageBase):
                                  'requirement {0}'.format(
                                      list(set_forbidden_properties)))
         StorageBase.__init__(self, name, _multi, warnings_only, doc, extra,
-                             calc_properties, requires, properties)
+                             calc_properties, requires, properties, allow_empty_list)
         if multi is not False and default is None:
             default = []
         self.impl_validate(default)
@@ -905,7 +905,7 @@ class SymLinkOption(OnlyOption):
                                'for symlink {0}').format(name))
         super(Base, self).__init__(name, undefined, undefined, undefined,
                                    undefined, undefined, undefined, undefined,
-                                   opt)
+                                   False, opt)
         self.commit()
 
     def __getattr__(self, name, context=undefined):