Feature/multiple validator

qcodes/tests/test_validators.py

@@ -3,7 +3,7 @@
 import numpy 
 
 from qcodes.utils.validators import (Validator, Anything, Bool, Strings,
-                                     Numbers, Ints, Enum, MultiType)
+                                     Numbers, Ints, Enum, Multiples, MultiType)
 
 
 class AClass:
@@ -379,6 +379,48 @@ def test_bad(self):
                 Enum(*enum)
 
 
+class TestMultiples(TestCase):
+    divisors = [3, 7, 11, 13]
+    not_divisors = [0, -1, -5, -1e15, 0.1, -0.1, 1.0, 3.5, -2.3e6, 5.5e15, 1.34e-10, -2.5e-5,
+                     math.pi, math.e, '', None, float("nan"), float("inf"),
+                     -float("inf"), '1', [], {}, [1, 2], {1: 1}, b'good',
+                     AClass, AClass(), a_func]
+    multiples = [0, 1, 10, -1, 100, 1000000, int(-1e15), int(1e15),
+            # warning: True==1 and False==0 - we *could* prohibit these, using
+            # isinstance(v, bool)
+            True, False,
+            # numpy scalars
+            numpy.int64(2)]
+    not_multiples = [0.1, -0.1, 1.0, 3.5, -2.3e6, 5.5e15, 1.34e-10, -2.5e-5,
+                     math.pi, math.e, '', None, float("nan"), float("inf"),
+                     -float("inf"), '1', [], {}, [1, 2], {1: 1}, b'good',
+                     AClass, AClass(), a_func]
+
+    def test_divisors(self):
+        for d in self.divisors:
+            n = Multiples(divisor=d)
+            for v in [d * e for e in self.multiples]:
+                n.validate(v)
+
+            for v in self.multiples:
+                if v == 0:
+                    continue
+                with self.assertRaises(ValueError):
+                    n.validate(v)
+
+            for v in self.not_multiples:
+                with self.assertRaises(TypeError):
+                    n.validate(v)
+
+        for d in self.not_divisors:
+            with self.assertRaises(TypeError):
+                n = Multiples(divisor=d)
+
+        n = Multiples(divisor=3, min_value=1, max_value=10)
+        self.assertEqual(
+            repr(n), '<Ints 1<=v<=10, Multiples of 3>')
+
+
 class TestMultiType(TestCase):
     def test_good(self):
         m = MultiType(Strings(2, 4), Ints(10, 1000))

qcodes/utils/validators.py

@@ -253,6 +253,36 @@ def validate(self, value, context=''):
         return self._validator.validate(value, context)
 
 
+class Multiples(Ints):
+    """
+    A validator that checks if a value is an integer multiple of a fixed devisor
+    This class extends validators.Ints such that the value is also checked for
+    being integer between an optional min_value and max_value. Furthermore this
+    validator checks that the value is an integer multiple of an fixed, integer
+    divisor. (i.e. value % divisor == 0)
+    Args:
+        divisor (integer), the value need the be a multiple of this divisor
+    Inherited Args (see validators.Ints):
+        max_value, value must be <= max_value
+        min_value, value must be >= min_value
+    """
+
+    def __init__(self, divisor=1, **kwargs):
+        super().__init__(**kwargs)
+        if not isinstance(divisor, int) or divisor <= 0:
+            raise TypeError('divisor must be a positive integer')
+        self._divisor = divisor
+
+    def validate(self, value, context=''):
+        super().validate(value=value, context=context)
+        if not value % self._divisor == 0:
+            raise ValueError('{} is not a multiple of {}; {}'.format(
+                repr(value), repr(self._divisor), context))
+
+    def __repr__(self):
+        return super().__repr__()[:-1] + ', Multiples of {}>'.format(self._divisor)
+
+
 class MultiType(Validator):
     """
     allow the union of several different validators