start implementing a validation layer, refs #215

owrx/property/validators.py

@@ -0,0 +1,42 @@
+from abc import ABC, abstractmethod
+
+
+class ValidatorException(Exception):
+    pass
+
+
+class Validator(ABC):
+    @staticmethod
+    def of(x):
+        if isinstance(x, Validator):
+            return x
+        if callable(x):
+            return LambdaValidator(x)
+        raise ValidatorException("Cannot create validator")
+
+    @abstractmethod
+    def isValid(self, value):
+        pass
+
+
+class LambdaValidator(Validator):
+    def __init__(self, c):
+        self.callable = c
+
+    def isValid(self, value):
+        return self.callable(value)
+
+
+class NumberValidator(Validator):
+    def isValid(self, value):
+        return isinstance(value, int) or isinstance(value, float)
+
+
+class IntegerValidator(Validator):
+    def isValid(self, value):
+        return isinstance(value, int)
+
+
+class StringValidator(Validator):
+    def isValid(self, value):
+        return isinstance(value, str)