Initial commit

nonzero.py

@@ -0,0 +1,25 @@
+"""
+Certain types of numerical values don't understand the concept of 0, usually ordinal
+Values: years, streets, storeys.
+"""
+
+class nz(int):
+    def check_for_0(s):
+        def f(self, other):
+            method = getattr(super(), s)
+            if self < 0 and method(other) >= 0:
+                return type(self)(method(other) + 1)
+            elif self > 0 and method(other) <= 0:
+                return type(self)(method(other) - 1)
+            else:
+                return type(self)(method(other))
+        return f
+
+    def __new__(cls, x):
+        if x == 0:
+            raise ValueError("0 is not a valid value")
+        else:
+            return super().__new__(cls, x)
+
+    __add__ = check_for_0('__add__')
+    __sub__ = check_for_0('__sub__')