fix: nullable 091

docs/tutorial/nullable.rst

@@ -6,8 +6,8 @@ Nullable variable
    Now in this section we would like to make it possible that it is not necessary to specify a value
    for a variable.
    
-   With rougail, it is possible for a variable's setttings have no value (nothing, null, None), 
-   that is, neither an assigned value nor a default value.
+   With rougail, it is possible for a variable's setttings to have no value (nothing, null, None), 
+   that is, neither a default value nor a user assigned value.
    
 .. prerequisites:: Prerequisites
 
@@ -33,18 +33,18 @@ Variable with the value "null"
 
 
 .. note:: It is important to keep in mind that in Rougail a variable is :term:`mandatory` by default, 
-         meaning that it must either have a default value set or a :term:`user data` value assigned in the :term:`user data file`\ .
+         meaning that it must either have a :term:`default value` set or a :term:`user data` value assigned in the :term:`user data file`\ .
          This is Rougail's default behavior.
 
          Besides, note that the explicit keyword to express the setting "no value, nothing" in YAML is the `null` explicit keyword.
 
 Here is how we are going to specify a "no value" (nothing, `null`) as a possible setting for the `address` variable in the `socks_proxy` family.
 
-We need to:
+There are a few things to set in the variable. We need to:
 
-- explicitely disable the default :term:`mandatory` behavior (we will set it to `false`,
-- redefine the 
-- define a default value of None (null).
+- explicitely disable the default :term:`mandatory` behavior of the `address` variable(just by setting it to `false`),
+- redefine the `address` variable inside the `socks_proxy` because this family uses the `proxy` type definition,
+- finally set the `address` default value to `null`.
 
 .. extinclude:: https://forge.cloud.silique.fr/stove/rougail-tutorials/raw/commit/v1.1_090/firefox/20-manual.yml
    :language: yaml
@@ -97,10 +97,86 @@ We need to:
     ...
 
 
-Here are somme maybe usefull explanations: 
+Some more, maybe usefull, explanations about our `address` variable in the `socks_proxy` family: 
 
 - Allowing the "no value, nothing" behavior is easy, we just add the `mandatory: false` attribute, 
 - we explicitely need to set the `redefine: true` attribute because in the type `proxy` type setting
   we didn't set the `mandatory` attribute to false, this is then a type redefinition,
 - finally we can set the `default: null` that means that we can set no value to our address variable.
 
+Note too that is is necessary to redefine (to set a `redefine` attribute) as soon as you 
+modify the type definition. Here we have set a default value to our `socks_proxy`'s `port` variable.
+We need then to redefine not only because of the `description` attribute but because of the default value too.
+
+
+Variables disabled when condition is null
+--------------------------------------------
+
+.. type-along:: For those who follow the tutorial with the help of the git repository
+
+    Now you need to checkout the :tutorial:`v1.1_091 <src/tag/v1.1_091/README.md>` version::
+
+          git switch --detach v1.1_091
+
+.. questions:: Question
+
+   But actually, why did we want a variable to be non-mandatory?
+
+Well, what we want is we need to be able to disable either the `port` and the `version` in case of the `address` has no value set:
+   
+.. extinclude:: https://forge.cloud.silique.fr/stove/rougail-tutorials/raw/commit/v1.1_091/firefox/20-manual.yml
+   :language: yaml
+   :caption: The :file:`firefox/20-manual.yml` structure file with the `disabled` set in case of the `address` has no value set
+
+..
+    %YAML 1.2
+    ---
+    version: 1.1
+
+    manual:
+
+      use_for_https: true  # Also use this proxy for HTTPS
+
+      https_proxy:
+        description: HTTPS Proxy
+        type: proxy
+        hidden:
+          variable: _.use_for_https
+
+        address:
+          redefine: true
+          description: HTTPS proxy address
+
+        port:
+          redefine: true
+          description: HTTPS proxy port
+
+      socks_proxy:
+        description: SOCKS Proxy
+        type: proxy
+
+        address:
+          redefine: true
+          description: SOCKS proxy address
+          default: null
+          mandatory: false
+
+        port:
+          redefine: true
+          description: SOCKS proxy port
+          default: 1080
+          disabled:
+            variable: _.address
+            when: null
+
+        version:
+          description: SOCKS host version used by proxy
+          choices:
+            - v4
+            - v5
+          default: v5
+          disabled:
+            variable: _.address
+            when: null
+    ...
+