Add new argument on_update_name as alternative to on_update

This addresses the problem of returning a context to the caller, as raised
in Jira CGP-181.

Author: Araneidae

docs/records.rst

@@ -101,6 +101,12 @@ specified:
     one callback is dispatched at a time, so if a callback blocks it will delay
     `on_update` callbacks for other records.
 
+`on_update_name`
+    This is an alternative form of `on_update` with the same behaviour: note
+    that at most one of `on_update` and `on_update_name` may be passed.  The
+    difference is that `on_update_name` is called with the record name as its
+    second argument after the value as the first argument.
+
 `validate`
     If used this should be set to a callable taking two arguments.  The first
     argument will be the record object, and the second will be the new value

docs/softioc.rst

@@ -222,6 +222,10 @@ functions:
     :func:`WaveformOut`).  This specifies a function that will be called after
     record processing has completed.
 
+`on_update_name`
+    This is an alternative callback function to use instead of `on_update`.
+    This function will be passed the record name as well as updated value.
+
 `validate`
     Also only available on OUT records, specifies a function called during
     record processing.  Note that this function is not cothread safe, that is to

example/testing.py

@@ -11,6 +11,8 @@
 def on_update(value):
     print('on_update', repr(value))
 
+def on_update_name(value, name):
+    print('on_update', name, ':', repr(value))
 
 t_ai        = aIn('AI')
 t_boolin    = boolIn('BOOLIN', 'True', 'False')
@@ -19,7 +21,7 @@ def on_update(value):
 t_mbbi      = mbbIn('MBBI', 'One', 'Two', 'Three')
 
 t_ao        = aOut      ('AO',
-    initial_value = 12.45, on_update = on_update)
+    initial_value = 12.45, on_update_name = on_update_name)
 t_boolout   = boolOut   ('BOOLOUT', 'Zero', 'One',
     initial_value = True, on_update = on_update)
 t_longout   = longOut   ('LONGOUT',

python/softioc/device.py

@@ -86,7 +86,18 @@ class ProcessDeviceSupportOut(ProcessDeviceSupportCore):
     __Callback = cothread.cothread._Callback()
 
     def __init__(self, name, **kargs):
-        self.__on_update = kargs.pop('on_update', None)
+        on_update = kargs.pop('on_update', None)
+        on_update_name = kargs.pop('on_update_name', None)
+        # At most one of on_update and on_update_name can be specified
+        assert on_update is None or on_update_name is None, \
+            'Cannot specify on_update and on_update_name together'
+        if on_update:
+            self.__on_update = on_update
+        elif on_update_name:
+            self.__on_update = lambda value: on_update_name(value, name)
+        else:
+            self.__on_update = None
+
         self.__validate  = kargs.pop('validate', None)
         self.__always_update = kargs.pop('always_update', False)
         self._value = kargs.pop('initial_value', None)

python/softioc/pythonSoftIoc.py

@@ -23,7 +23,8 @@ def __init__(self, builder, device, name, **fields):
         # remaining arguments are passed to the builder.  It's a shame we
         # have to maintain this separately from the corresponding device list.
         DeviceKeywords = [
-            'on_update', 'validate', 'initial_value', 'always_update']
+            'on_update', 'on_update_name', 'validate',
+            'initial_value', 'always_update']
         device_kargs = {}
         for keyword in DeviceKeywords:
             if keyword in fields: