Moved casting function in rstring

rstring now has an autocast() function that returns the automatic casting
for that value.
The casting is cached so is really performed only once, at most, during
the lifetime of the object.

relational/relation.py

@@ -100,18 +100,6 @@ class relation (object):
             ','.join(self.header.attributes) , ','.join(other.header.attributes)
             ))
 
-    def _autocast(self, string):
-        '''Depending on the regexp matched by the string,
-        it will perform automatic casting'''
-        if len(string) > 0 and string.isInt():
-            return int(string)
-        elif len(string) > 0 and string.isFloat():
-            return float(string)
-        elif len(string) > 0 and string.isDate():
-            return rdate(string)
-        else:
-            return string
-
     def selection(self, expr):
         '''Selection, expr must be a valid boolean expression, can contain field names,
         constant, math operations and boolean ones.'''
@@ -121,7 +109,7 @@ class relation (object):
         for i in self.content:
             # Fills the attributes dictionary with the values of the tuple
             for j in range(len(self.header.attributes)):
-                attributes[self.header.attributes[j]] = self._autocast(i[j])
+                attributes[self.header.attributes[j]] = i[j].autocast()
 
             try:
                 if eval(expr, attributes):
@@ -448,7 +436,7 @@ class relation (object):
         # new_content=[] #New content of the relation
         for i in self.content:
             for j in range(len(self.header.attributes)):
-                attributes[self.header.attributes[j]] = self._autocast(i[j])
+                attributes[self.header.attributes[j]] = i[j].autocast()
 
             if eval(expr, attributes):  # If expr is true, changing the tuple
                 affected += 1

relational/rtypes.py

@@ -28,6 +28,25 @@ import re
 class rstring (str):
 
     '''String subclass with some custom methods'''
+    def autocast(self):
+        '''
+        Returns the automatic cast for this
+        value.
+        '''
+        try:
+            return self._autocast
+        except:
+            pass
+
+        self._autocast = self
+        if len(self) > 0:
+            if self.isInt():
+                self._autocast = int(self)
+            elif self.isFloat():
+                self._autocast = float(self)
+            elif self.isDate():
+                self._autocast = rdate(self)
+        return self._autocast
 
     def isInt(self):
         '''Returns true if the string represents an int number
@@ -35,16 +54,10 @@ class rstring (str):
         the following regexp:
         r'^[\+\-]{0,1}[0-9]+$'
         '''
-        try:
-            return self._isint
-        except:
-            pass
-
         if re.match(r'^[\+\-]{0,1}[0-9]+$', self) == None:
-            self._isint = False
+            return False
         else:
-            self._isint = True
-        return self._isint
+            return True
 
     def isFloat(self):
         '''Returns true if the string represents a float number
@@ -52,16 +65,10 @@ class rstring (str):
         the following regexp:
             r'^[\+\-]{0,1}[0-9]+(\.([0-9])+)?$'
         '''
-        try:
-            return self._isfloat
-        except:
-            pass
-
         if re.match(r'^[\+\-]{0,1}[0-9]+(\.([0-9])+)?$', self) == None:
-            self._isfloat = False
+            return False
         else:
-            self._isfloat = True
-        return self._isfloat
+            return True
 
     def isDate(self):
         '''Returns true if the string represents a date,