From d48a3ab99919df8861a57ec3191eb5df5251483b Mon Sep 17 00:00:00 2001
From: Julien R M Lhermitte <jrmlhermitte@bnl.gov>
Date: Mon, 19 Mar 2018 21:13:35 -0400
Subject: [PATCH] Ensure that changes to value, limits and fit update the
 parent

---
 hkl/calc.py   | 10 +++++---
 hkl/engine.py | 66 +++++++++++++++++++++++++++++++++++++++++++++++++++
 2 files changed, 73 insertions(+), 3 deletions(-)

diff --git a/hkl/calc.py b/hkl/calc.py
index 50f761a3..788f9491 100644
--- a/hkl/calc.py
+++ b/hkl/calc.py
@@ -5,7 +5,7 @@
 
 import numpy as np
 
-from .engine import (Engine, Parameter)
+from .engine import (Engine, CalcParameter)
 from .sample import HklSample
 from . import util
 from .util import hkl_module
@@ -399,16 +399,20 @@ def _get_axis_by_name(self, name):
         name = self._axis_name_to_original.get(name, name)
         return self._geometry.axis_get(name)
 
+    def _set_axis_by_name(self, name, axis):
+        self._geometry.axis_set(name, axis)
+
     @property
     def units(self):
         '''The units used for calculations'''
         return self._unit_name
 
     def __getitem__(self, axis):
-        return Parameter(self._get_axis_by_name(axis),
+        return CalcParameter(self._get_axis_by_name(axis),
                          units=self._unit_name,
                          name=axis,
-                         inverted=axis in self._inverted_axes)
+                         inverted=axis in self._inverted_axes,
+                             geometry=self._geometry)
 
     def __setitem__(self, axis, value):
         param = self[axis]
diff --git a/hkl/engine.py b/hkl/engine.py
index 20fa457c..cacaa325 100644
--- a/hkl/engine.py
+++ b/hkl/engine.py
@@ -40,6 +40,10 @@ def name(self):
             return '{} (internally: {})'.format(self._name, name)
         return name
 
+    @property
+    def param_name(self):
+        return self._param.name_get()
+
     @property
     def value(self):
         return self._param.value_get(self._units)
@@ -267,3 +271,65 @@ def _repr_info(self):
     def __repr__(self):
         return '{}({})'.format(self.__class__.__name__,
                                ', '.join(self._repr_info()))
+
+# the parameter for the calc object
+# this is a fix for backwards compatibility
+# when updating parameters we need to update the parent geometry object
+class CalcParameter(Parameter):
+    def __init__(self, *args, geometry=None, **kwargs):
+        '''
+            Like calc parameter but needs reference to a geometry object.
+            Updates to the parameter should be propagated back to the geometry.
+        '''
+        super().__init__(*args, **kwargs)
+        self._geometry = geometry
+
+    @property
+    def limits(self):
+        if self._inverted:
+            low, high = self._param.min_max_get(self._units)
+            return [-high, -low]
+        else:
+            return self._param.min_max_get(self._units)
+
+    @limits.setter
+    def limits(self, lims):
+        low, high = lims
+        if self._inverted:
+            low, high = -high, -low
+        self._param.min_max_set(low, high, self._units)
+        if self._geometry is not None:
+            # param name is the true name of axis
+            axis = self._geometry.axis_get(self.param_name)
+            axis.min_max_set(low, high, self._units)
+            self._geometry.axis_set(self.param_name, axis)
+
+    @property
+    def value(self):
+        return self._param.value_get(self._units)
+
+    @value.setter
+    def value(self, value):
+        if self._inverted:
+            value *= -1.0
+
+        self._param.value_set(value, self._units)
+        if self._geometry is not None:
+            # param name is the true name of axis
+            axis = self._geometry.axis_get(self.param_name)
+            axis.value_set(value, self._units)
+            self._geometry.axis_set(self.param_name, axis)
+
+    @property
+    def fit(self):
+        '''True if the parameter can be fit or not'''
+        return bool(self._param.fit_get())
+
+    @fit.setter
+    def fit(self, fit):
+        self._param.fit_set(int(fit))
+        if self._geometry is not None:
+            # param name is the true name of axis
+            axis = self._geometry.axis_get(self.param_name)
+            axis.fit_set(fit)
+            self._geometry.axis_set(self.param_name, axis)