Fix a regression bug in AtGetRingProperties (#701)

* fix missing 'cavpts' in ring parameters

atmat/lattice/atGetRingProperties.m

@@ -74,26 +74,25 @@
 [show_all, varargin]=getflag(varargin, 'all');
 idx=atlocateparam(ring);
 if isempty(idx)
-%   t1='Slow access to properties because there is no RingParam element.';
-%   t2='Consider adding it with the command: ">> ring=atSetRingProperties(ring)".';
-%   warning('AT:NoRingParam', '%s\n%s', t1, t2);
+    t1='Slow access to properties because there is no RingParam element.';
+    t2='Consider adding it with the command: ">> ring=atSetRingProperties(ring)".';
+    warning('AT:NoRingParam', '%s\n%s', t1, t2);
     props=struct();
 else
     props=rmfield(ring{idx},{'Length','Class','PassMethod'});
 end
 if isempty(varargin)
-    [props,~]=atparamscan(ring,props,'FamName','Energy','Periodicity',...
-        'Particle','cell_harmnumber','cavpts');
-    props.Particle=atparticle.loadobj(props.Particle);
-    props.HarmNumber=props.Periodicity*props.cell_harmnumber;
+    prmlist = {'FamName','Energy','Periodicity', 'Particle',...
+        'cell_harmnumber', 'HarmNumber','cavpts'};
     if show_all
-        prmlist={'beta', 'gamma', 'BRho', 'rf_frequency', 'rf_voltage', 'rf_timelag',...
-            'mcf', 'slip_factor', 'radiation', 'is_6d', 'has_cavity',...
-            'Circumference', 'revolution_frequency',...     
-            'cell_length', 'cell_rf_voltage', 'cell_revolution_frequency'};
-        [~,prms]=atparamscan(ring,props,prmlist{:});
-        cellfun(@setprop,prmlist,prms);
+        prmlist = [prmlist {'beta', 'gamma', 'BRho', 'rf_frequency',...
+            'rf_voltage', 'rf_timelag', 'mcf', 'slip_factor',...
+            'radiation', 'is_6d', 'has_cavity', 'Circumference',...
+            'revolution_frequency', 'cell_length', 'cell_rf_voltage',...
+            'cell_revolution_frequency'}];
     end
+    [~, prms] = atparamscan(ring, props, prmlist{:});
+    cellfun(@setprop,  prmlist, prms);
     varargout={props,idx};
 else
     [~,varargout]=atparamscan(ring,props,varargin{:});