Update files after the review

Author: xuniq

doc/reference/reference_lua/box_events.rst

@@ -4,7 +4,7 @@ Event watchers
 ==============
 
 The ``box`` module contains some features related to event subscriptions, also known as :term:`watchers <watcher>`.
-The subscriptions are used to inform a client about server-side :term:`events <event>`.
+The subscriptions are used to inform a client about the server-side :term:`events <event>`.
 Each event subscription is defined by a certain key.
 
 ..  glossary::
@@ -41,7 +41,7 @@ after the registration of the watcher.
 The watcher callback takes two arguments.
 The first argument is a name of the key for which it was registered.
 The second one contains current key data.
-The callback is always invoked in a new fiber. It means that is is okay to yield in it.
+The callback is always invoked in a new fiber. It means that is allowed to yield in it.
 A watcher callback is never executed in parallel with itself.
 If the key is updated while the watcher callback is running, the callback will be invoked again with the new
 value as soon as it returns.
@@ -71,7 +71,7 @@ Below is a list of all functions and members related to watchers or events.
         *  - :doc:`./box_events/broadcast`
            - Update a state.
 
-        *  - :ref:`˜Built-in events <system-events>`
+        *  - :ref:`Built-in events <system-events>`
            - Predefined events in Tarantool
 
 .. toctree::

doc/reference/reference_lua/box_events/broadcast.rst

@@ -22,7 +22,7 @@ box.broadcast()
 
     ..  code-block:: lua
 
-        -- Broadcast value 123 for the 'foo' key.
-        box.broadcast('foo', 123)
+        -- Broadcast value 42 for the 'foo' key.
+        box.broadcast('foo', 42)
 
 

doc/reference/reference_lua/box_events/system_events.rst

@@ -19,6 +19,12 @@ The events are available from the beginning as non-:ref:`MP_NIL <box_protocol-no
 If a watcher subscribes to a system event before it has been broadcast,
 it receives an empty table for the event value.
 
+The event is generated when there is a change in any of the values listed in the event.
+For example, see the parameters in the ``box.id`` event below -- ``id``, ``instance_uuid``, and ``replicaset_uuid``.
+Suppose the ``ìd`` value (``box.info.id``) has changed.
+This triggers the ``box.info`` event, which states that the value of ``box.info.id`` has changed,
+while ``box.info.uuid`` and ``box.info.cluster.uuid`` remain the same.
+
 box.id
 ~~~~~~
 
@@ -33,7 +39,6 @@ Value changes are rare.
     The value is unknown before the ``box.cfg`` call.
 
 *   ``replicaset_uuid``: the value is unknown until the instance joins a replicaset or boots a new one.
-    The events start working before that -- right with the start of the listen.
 
 ..  code-block:: lua
 
@@ -99,28 +104,18 @@ Usage example
 
 ..  code-block:: lua
 
-    conn = net.box.connect(URI)
+    local conn = net.box.connect(URI)
+    local log = require('log')
     -- Subscribe to updates of key 'box.id'
-    w = conn:watch('box.id', function(key, value)
+    local w = conn:watch('box.id', function(key, value)
         assert(key == 'box.id')
-        -- do something with value
-    end)
-    -- or to updates of key 'box.status'
-    w = conn:watch('box.status', function(key, value)
-        assert(key == 'box.status')
-        -- do something with value
-    end)
-    -- or to updates of key 'box.election'
-    w = conn:watch('box.election', function(key, value)
-        assert(key == 'box.election')
-        -- do something with value
-    end)
-    -- or to updates of key 'box.schema'
-    w = conn:watch('box.schema', function(key, value)
-        assert(key == 'box.schema')
-        -- do something with value
+        log.info("The box.id value is '%s'", value)
     end)
-    -- Unregister the watcher when it's no longer needed.
+
+If you want to unregister the watcher when it's no longer needed, use the following command:
+
+..  code-block:: lua
+
     w:unregister()
 
 

doc/reference/reference_lua/box_events/watch.rst

@@ -13,7 +13,7 @@ box.watch()
 
     :return: a watcher handle. The handle consists of one method -- ``unregister()``, which unregisters the watcher.
 
-    To read more about watchers, see the `Functions for watchers <box-watchers>` section.
+    To read more about watchers, see the :ref:`Functions for watchers <box-watchers>` section.
 
     ..  note::
 
@@ -25,13 +25,19 @@ box.watch()
 
     ..  code-block:: lua
 
-        -- Broadcast value 123 for the 'foo' key.
-        box.broadcast('foo', 123)
+        -- Broadcast value 42 for the 'foo' key.
+        box.broadcast('foo', 42)
+
+        local log = require('log')
         -- Subscribe to updates of the 'foo' key.
-        w = box.watch('foo', function(key, value)
+        local w = box.watch('foo', function(key, value)
             assert(key == 'foo')
-            -- do something with value
+            log.info("The box.id value is '%d'", value)
         end)
-        -- Unregister the watcher when it is no longer needed.
+
+    If you don't need the watcher anymore, you can unregister it using the command below:
+
+    ..  code-block:: lua
+
         w:unregister()
 

doc/reference/reference_lua/net_box.rst

@@ -1,4 +1,4 @@
-..  _net_box-module:
+zc..  _net_box-module:
 
 --------------------------------------------------------------------------------
 Module net.box
@@ -545,7 +545,7 @@ Below is a list of all ``net.box`` functions.
         :param function func:  a callback to invoke when the key value is updated
         :return: a watcher handle. The handle consists of one method -- ``unregister()``, which unregisters the watcher.
 
-        To read more about watchers, see the `Functions for watchers <box-watchers>` section.
+        To read more about watchers, see the :ref:`Functions for watchers <box-watchers>` section.
 
         The method has the same syntax as the :doc:`box.watch() </reference/reference_lua/box_events/broadcast>`
         function, which is used for subscribing to events locally.
@@ -570,20 +570,25 @@ Below is a list of all ``net.box`` functions.
 
         ..  code-block:: lua
 
-            -- Broadcast value 123 for the key 'foo'.
-            box.broadcast('foo', 123)
+            -- Broadcast value 42 for the 'foo' key.
+            box.broadcast('foo', 42)
 
         Client:
 
         ..  code-block:: lua
 
             conn = net.box.connect(URI)
+            local log = require('log')
             -- Subscribe to updates of the 'foo' key.
             w = conn:watch('foo', function(key, value)
                 assert(key == 'foo')
-                -- do something with value
+                log.info("The box.id value is '%d'", value)
             end)
-            -- Unregister the watcher if it is no longer needed.
+
+        If you don't need the watcher anymore, you can unregister it using the command below:
+
+        ..  code-block:: lua
+
             w:unregister()
 
     .. _conn-timeout: