Keep phase fraction constraints in WPPF after load

After loading parameters (either from a state file or importing params
from an HDF5 file), if there was an expression on a parameter, restore
that parameter after the load.

Fixes: #1923

Signed-off-by: Patrick Avery <[email protected]>

Author: psavery

hexrdgui/calibration/wppf_options_dialog.py

@@ -803,8 +803,13 @@ def params_dict(self, v):
             if key not in self.params:
                 continue
 
+            old_param = self.params[key]
             self.params[key] = dict_to_param(val)
 
+            if old_param.expr:
+                # If there was an expression, restore that expression
+                self.params[key].expr = old_param.expr
+
     def load_settings(self):
         settings = HexrdConfig().config['calibration'].get('wppf')
         if not settings:
@@ -1688,8 +1693,11 @@ def load_params(self, filename):
         self.validate_import_params(import_params, filename)
 
         # Keep the ordering the same as the GUI currently has
-        for key in self.params.keys():
+        for key, old_param in self.params.items():
             self.params[key] = dict_to_param(import_params[key])
+            if old_param.expr:
+                # If there was an expression, restore that expression
+                self.params[key].expr = old_param.expr
 
         self.update_tree_view()
         self.save_settings()