added dj.GeneralRelvar/pair to facilitate querying pairs of tupes from a relation

Author: dimitri-yatsenko

+dj/GeneralRelvar.m

@@ -322,7 +322,7 @@ function export(self, outfilePrefix, mbytesPerChunk)
             tuplesPerChunk = 1;
 
             % enclose in transaction to ensure that LIMIT and OFFSET work correctly
-            self.schema.conn.startTransaction
+            self.conn.startTransaction
 
             savedTuples = 0;
             savedMegaBytes = 0;
@@ -346,7 +346,7 @@ function export(self, outfilePrefix, mbytesPerChunk)
                 fileNumber = fileNumber + 1;
             end
 
-            self.schema.conn.cancelTransaction
+            self.conn.cancelTransaction
 
             function mbytes = sizeMB(variable) %#ok<INUSD>
                 mbytes = whos('variable');
@@ -543,18 +543,31 @@ function restrict(self, varargin)
                     'dj.GeneralRelvar/mtimes requires another relvar as operand'))
             end
             ret = init(dj.GeneralRelvar, 'join', {self arg});
-        end
+        end        
 
+        function ret = pair(self, varargin)
+            % dj.GeneralRelvar/pair - a natural join with itself with some
+            % attributes renamed.
+            % This facilitates a common use case when pairs of tuples from the
+            % relation need to be examined.
+            
+            renamedAttrs1 = cellfun(@(s) sprintf('%s->%s1',s,s), varargin,'uni',false);
+            renamedAttrs2 = cellfun(@(s) sprintf('%s->%s2',s,s), varargin,'uni',false);
+            ret = self.pro(renamedAttrs1{:})*self.pro(renamedAttrs2{:});
+        end
 
 
         %%%%% DEPRECATED RELATIIONAL OPERATORS (for backward compatibility)
         function ret = times(self, arg)
+            warning 'The relational operator .* (semijoin) will be removed in a future release.  Please use & instead.'
             ret = self & arg;
         end
         function ret = rdivide(self, arg)
+            warning 'The relational operator / (antijoin) will be removed in a future release.  Please use - instead.'
             ret = self - arg;
         end
         function ret = plus(self, arg)
+            warning 'The relational operator + (union) will be removed in a future release.  Please use | instead'
             ret = self | arg;
         end
 

+dj/Schema.m

@@ -110,7 +110,7 @@ function makeClass(self, className)
             if numel(existingTable)
                 fprintf(f, '%s', existingTable.re);
                 tab = dj.Table([self.package '.' className]);
-                parents = tab.parents;
+                parents = cellfun(@(x) self.conn.tableToClass(x), tab.parents, 'uni', false);
             else
                 fprintf(f, '%%{\n');
                 fprintf(f, '%s.%s (%s) # my newest table\n', self.package, className, tier);

+dj/version.m

@@ -1,10 +1,10 @@
 function varargout = version
 % report DataJoint version
 
-v = struct('major',2,'minor',7,'bugfix',5);
+v = struct('major',2,'minor',7,'bugfix',6);
 
 if nargout
     varargout{1}=v;
 else
     fprintf('\nDataJoint version %d.%d.%d\n\n', v.major, v.minor, v.bugfix)
-end
+end