adjust mechanism of write function with iohandler

if a write_<parameter> function is defined and <parameter> has an
iohandler, the handlers write function is not called automatically.
It has to be called explicitly in the write_<param> function, if
needed.

reasons:
- the previous logic when a wrapped write function is already present, and a
  handler is defined on the specialized class, did not work, and is not
  easy to solve properly
- it is probably anyway better to call the handlers write function explicitly
  instead of automatically depending on the return value

Change-Id: I04f0849b6cc3fb9979c0f5ac8245a6ab4bf23072
Reviewed-on: https://forge.frm2.tum.de/review/c/sine2020/secop/playground/+/22565
Tested-by: JenkinsCodeReview <bjoern_pedersen@frm2.tum.de>
Reviewed-by: Markus Zolliker <markus.zolliker@psi.ch>

secop/iohandler.py

@@ -49,9 +49,8 @@ def change_<group>(self, change):
     # which will be formatted by the handler, or None. The latter is used only in some
     # special cases, when nothing has to be written.
 
-A write_<parameter> method may be implemented in addition. In that case, it is executed
+A write_<parameter> method may be implemented in addition. In that case, the handlers write
-before change_<group>. write_<parameters> may return None or Done, in these cases
+method has to be called explicitly int the write_<parameter> method, if needed.
-change_<group> is not called.
 """
 import re
 
@@ -263,6 +262,8 @@ class IOHandler(IOHandlerBase):
         if self._module_class != modclass:
             raise ProgrammingError("the handler '%s' for '%s.%s' is already used in module '%s'"
                                    % (self.group, modclass.__name__, pname, self._module_class.__name__))
+        # self.change might be needed even when get_write_func was not called
+        self.change = getattr(self._module_class, 'change_' + self.group, None)
         self.parameters.add(pname)
         self.analyze = getattr(modclass, 'analyze_' + self.group)
         return self.read
@@ -295,7 +296,6 @@ class IOHandler(IOHandlerBase):
         If pre_wfunc is given, it is to be called before change_<group>.
         May be overriden to return None, if not used
         """
-        self.change = getattr(self._module_class, 'change_' + self.group)
 
         def wfunc(module, value, hdl=self, pname=pname):
             hdl.write(module, pname, value)

secop/metaclass.py

@@ -165,29 +165,27 @@ class ModuleMeta(PropertyMeta):
 
             if not pobj.readonly:
                 wfunc = attrs.get('write_' + pname, None)
-                for base in bases:
+                if wfunc is None:  # ignore the handler, if a write function is present
-                    if wfunc is not None:
+                    wfunc = pobj.handler.get_write_func(pname) if pobj.handler else None
-                        break
+                    for base in bases:
-                    wfunc = getattr(base, 'write_' + pname, None)
+                        if wfunc is not None:
+                            break
+                        wfunc = getattr(base, 'write_' + pname, None)
 
                 # create wrapper except when write function is already wrapped
                 if wfunc is None or getattr(wfunc, '__wrapped__', False) is False:
 
-                    # append write function from handler, to be called after wfunc
+                    def wrapped_wfunc(self, value, pname=pname, wfunc=wfunc):
-                    wfuncs = (wfunc, pobj.handler.get_write_func(pname) if pobj.handler else None)
-
-                    def wrapped_wfunc(self, value, pname=pname, wfuncs=wfuncs):
                         self.log.debug("check validity of %s = %r" % (pname, value))
                         pobj = self.accessibles[pname]
                         value = pobj.datatype(value)
-                        for wfunc in filter(None, wfuncs):
+                        if wfunc:
                             self.log.debug('calling %s %r(%r)' % (wfunc.__name__, wfunc, value))
                             returned_value = wfunc(self, value)
                             if returned_value is Done:  # the setter is already triggered
                                 return getattr(self, pname)
-                            if returned_value is None:  # goodie: accept missing return value
+                            if returned_value is not None:  # goodie: accept missing return value
-                                break  # handler is not called in this case
+                                value = returned_value
-                            value = returned_value
                         setattr(self, pname, value)
                         return value
 

secop_psi/ppms.py

@@ -49,6 +49,7 @@ from secop.metaclass import Done
 try:
     import secop_psi.ppmswindows as ppmshw
 except ImportError:
+    print('use simulation instead')
     import secop_psi.ppmssim as ppmshw
 
 
@@ -231,7 +232,7 @@ class DriverChannel(Channel):
         return dict(current=current, powerlimit=powerlimit)
 
     def change_drvout(self, change):
-        self.readValues()
+        change.readValues()
         return change.current, change.powerlimit
 
 
@@ -274,7 +275,7 @@ class BridgeChannel(Channel):
             )
 
     def change_bridge(self, change):
-        self.readValues()
+        change.readValues()
         if change.enabled:
             return self.no, change.excitation, change.powerlimit, change.dcflag, change.readingmode, change.voltagelimit
         return self.no, 0, 0, change.dcflag, change.readingmode, 0
@@ -504,17 +505,20 @@ class Temp(PpmsMixin, Drivable):
         self._status_before_change = self.status
         self.status = [self.Status.BUSY, 'changed target']
         self._last_change = time.time()
-        return target
+        self.temp.write(self, 'target', target)
+        return Done
 
     def write_approachmode(self, value):
         if self.isDriving():
-            return value
+            self.temp.write(self, 'approachmode', value)
-        return None  # change_temp will not be called, as this would trigger an unnecessary T change
+            return Done
+        return None  # do not execute TEMP command, as this would trigger an unnecessary T change
 
     def write_ramp(self, value):
         if self.isDriving():
-            return value
+            self.temp.write(self, 'ramp', value)
-        return None  # change_temp will not be called, as this would trigger an unnecessary T change
+            return Done
+        return None  # do not execute TEMP command, as this would trigger an unnecessary T change
 
     def calc_expected(self, target, ramp):
         self._expected_target_time = time.time() + abs(target - self.value) * 60.0 / max(0.1, ramp)
@@ -638,7 +642,8 @@ class Field(PpmsMixin, Drivable):
         self._stopped = False
         self._last_change = time.time()
         self.status = [self.Status.BUSY, 'changed target']
-        return target
+        self.field.write(self, 'target', target)
+        return Done
 
     def write_persistentmode(self, mode):
         if abs(self.target - self.value) <= 2e-5 and mode == self.persistentmode:
@@ -647,17 +652,20 @@ class Field(PpmsMixin, Drivable):
         self._status_before_change = list(self.status)
         self._stopped = False
         self.status = [self.Status.BUSY, 'changed persistent mode']
-        return mode
+        self.field.write(self, 'persistentmode', mode)
+        return Done
 
     def write_ramp(self, value):
         if self.isDriving():
-            return value
+            self.field.write(self, 'ramp', value)
-        return None  # change_field will not be called, as this would trigger a ramp up of leads current
+            return Done
+        return None  # do not execute FIELD command, as this would trigger a ramp up of leads current
 
     def write_approachmode(self, value):
         if self.isDriving():
-            return value
+            self.field.write(self, 'approachmode', value)
-        return None  # change_temp will not be called, as this would trigger a ramp up of leads current
+            return Done
+        return None  # do not execute FIELD command, as this would trigger a ramp up of leads current
 
     def do_stop(self):
         if not self.isDriving():
@@ -750,12 +758,14 @@ class Position(PpmsMixin, Drivable):
         self._stopped = False
         self._last_change = 0
         self._status_before_change = self.status
-        return target
+        self.move.write(self, 'target', target)
+        return Done
 
     def write_speed(self, value):
         if self.isDriving():
-            return value
+            self.move.write(self, 'speed', value)
-        return None  # change_move not called as this would trigger an unnecessary move
+            return Done
+        return None  # do not execute MOVE command, as this would trigger an unnecessary move
 
     def do_stop(self):
         if not self.isDriving():