Classes have now names that begin with uppercase

This is more Pythonic and makes the code more readable.

Backwards compatibility is provided by giving an alias with the
previous name of the class.

It will not be broken until the next major release.

relational/maintenance.py

@@ -60,7 +60,7 @@ def check_latest_version():
     return s.decode().strip()
 
 
-class user_interface (object):
+class UserInterface (object):
 
     '''It is used to provide services to the user interfaces, in order to
     reduce the amount of duplicated code present in different user interfaces.

relational/parser.py

@@ -99,7 +99,7 @@ class CallableString(str):
         return eval(self, context)
 
 
-class node (object):
+class Node (object):
 
     '''This class is a node of a relational expression. Leaves are relations
     and internal nodes are operations.
@@ -416,7 +416,5 @@ if __name__ == "__main__":
         e = input("Expression: ")
         print (parse(e))
 
-    # b=u"σ age>1 and skill=='C' (peopleᐅᐊskills)"
-    # print b[0]
-    # parse(b)
-    pass
+#Backwards compatibility
+node = Node

relational/relation.py

@@ -26,7 +26,7 @@ from collections import deque
 from relational.rtypes import *
 
 
-class relation (object):
+class Relation (object):
 
     '''
     This object defines a relation (as a group of consistent tuples) and operations.
@@ -57,11 +57,11 @@ class relation (object):
 
         if len(filename) == 0:  # Empty relation
             self.content = set()
-            self.header = header([])
+            self.header = Header([])
             return
         with open(filename) as fp:
             reader = csv.reader(fp)  # Creating a csv reader
-            self.header = header(next(reader))  # read 1st line
+            self.header = Header(next(reader))  # read 1st line
             self.content = set()
             attributes = len(self.header)
 
@@ -121,7 +121,7 @@ class relation (object):
         Selection, expr must be a valid Python expression; can contain field names.
         '''
         newt = relation()
-        newt.header = header(self.header)
+        newt.header = Header(self.header)
         for i in self.content:
             # Fills the attributes dictionary with the values of the tuple
             attributes = {attr: i[j].autocast()
@@ -148,7 +148,7 @@ class relation (object):
                 'Unable to perform product on relations with colliding attributes'
             )
         newt = relation()
-        newt.header = header(self.header + other.header)
+        newt.header = Header(self.header + other.header)
 
         for i in self.content:
             for j in other.content:
@@ -178,7 +178,7 @@ class relation (object):
         newt = relation()
         # Create the header
         h = (self.header[i] for i in ids)
-        newt.header = header(h)
+        newt.header = Header(h)
 
         # Create the body
         for i in self.content:
@@ -213,7 +213,7 @@ class relation (object):
         '''
         other = self._rearrange(other)  # Rearranges attributes' order
         newt = relation()
-        newt.header = header(self.header)
+        newt.header = Header(self.header)
 
         newt.content = self.content.intersection(other.content)
         return newt
@@ -224,7 +224,7 @@ class relation (object):
         '''
         other = self._rearrange(other)  # Rearranges attributes' order
         newt = relation()
-        newt.header = header(self.header)
+        newt.header = Header(self.header)
 
         newt.content = self.content.difference(other.content)
         return newt
@@ -261,7 +261,7 @@ class relation (object):
         '''
         other = self._rearrange(other)  # Rearranges attributes' order
         newt = relation()
-        newt.header = header(self.header)
+        newt.header = Header(self.header)
 
         newt.content = self.content.union(other.content)
         return newt
@@ -298,7 +298,7 @@ class relation (object):
         # Creating the header with all the fields, done like that because order is
         # needed
         h = (i for i in other.header if i not in shared)
-        newt.header = header(chain(self.header, h))
+        newt.header = Header(chain(self.header, h))
 
         # Shared ids of self
         sid = self.header.getAttributesId(shared)
@@ -342,7 +342,7 @@ class relation (object):
         # Creating the header with all the fields, done like that because order is
         # needed
         h = (i for i in other.header if i not in shared)
-        newt.header = header(chain(self.header, h))
+        newt.header = Header(chain(self.header, h))
 
         # Shared ids of self
         sid = self.header.getAttributesId(shared)
@@ -484,14 +484,14 @@ class relation (object):
         return len(self.content) - l
 
 
-class header(tuple):
+class Header(tuple):
 
     '''This class defines the header of a relation.
     It is used within relations to know if requested operations are accepted'''
 
     # Since relations are mutalbe we explicitly block hashing them
     def __new__(cls, fields):
-        return super(header, cls).__new__(cls, tuple(fields))
+        return super(Header, cls).__new__(cls, tuple(fields))
 
     def __init__(self, *args, **kwargs):
         '''Accepts a list with attributes' names. Names MUST be unique'''
@@ -504,7 +504,7 @@ class header(tuple):
             raise Exception('Attribute names must be unique')
 
     def __repr__(self):
-        return "header(%s)" % super(header, self).__repr__()
+        return "Header(%s)" % super(Header, self).__repr__()
 
     def rename(self, params):
         '''Returns a new header, with renamed fields.
@@ -520,7 +520,7 @@ class header(tuple):
                 attrs[id_] = new
             except:
                 raise Exception('Field not found: %s' % old)
-        return header(attrs)
+        return Header(attrs)
 
     def sharedAttributes(self, other):
         '''Returns how many attributes this header has in common with a given one'''
@@ -537,3 +537,7 @@ class header(tuple):
     def getAttributesId(self, param):
         '''Returns a list with numeric index corresponding to field's name'''
         return [self.index(i) for i in param]
+
+#Backwards compatibility
+relation = Relation
+header = Header

relational/rtypes.py

@@ -26,7 +26,7 @@ import re
 RELATION_NAME_REGEXP = r'^[_a-zA-Z]+[_a-zA-Z0-9]*$'
 
 
-class rstring (str):
+class Rstring (str):
 
     '''String subclass with some custom methods'''
 
@@ -112,7 +112,7 @@ class rstring (str):
             return self._date
 
 
-class rdate (object):
+class Rdate (object):
 
     '''Represents a date'''
 
@@ -158,8 +158,11 @@ class rdate (object):
     def __sub__(self, other):
         return (self.intdate - other.intdate).days
 
-
 def is_valid_relation_name(name):
     '''Checks if a name is valid for a relation.
     Returns boolean'''
     return re.match(RELATION_NAME_REGEXP, name) != None
+
+#Backwards compatibility
+rdate = Rdate
+rstring = Rstring

relational_gui/guihandler.py

@@ -18,7 +18,7 @@
 from PyQt5 import QtCore, QtWidgets, QtWidgets
 
 from relational import relation, parser, optimizer, rtypes
-from relational.maintenance import user_interface
+from relational.maintenance import UserInterface
 
 from relational_gui import about
 from relational_gui import survey
@@ -36,7 +36,7 @@ class relForm(QtWidgets.QMainWindow):
         self.selectedRelation = None
         self.ui = ui
         self.qcounter = 1  # Query counter
-        self.user_interface = user_interface()
+        self.user_interface = UserInterface()
 
         self.settings = QtCore.QSettings()