Add NumberMeta for floats and ints.

malcolm/core/__init__.py

@@ -1,2 +1,3 @@
 # Need to import these so that the register hooks are called
 from malcolm.core.stringmeta import StringMeta  # noqa
+from malcolm.core.numbermeta import NumberMeta  # noqa

malcolm/core/numbermeta.py

@@ -0,0 +1,40 @@
+from malcolm.core.attributemeta import AttributeMeta
+
+from pkg_resources import require
+require("numpy")
+import numpy as np
+
+
+_metas = {
+    np.int32:"malcolm:core/Int:1.0",
+    np.float64:"malcolm:core/Float:1.0"
+    }
+
+@AttributeMeta.register_subclass(_metas[np.int32], np.int32)
+@AttributeMeta.register_subclass(_metas[np.float64], np.float64)
+class NumberMeta(AttributeMeta):
+    """Meta object containing information for a numerical value"""
+
+    def __init__(self, name, description, dtype):
+        super(NumberMeta, self).__init__(name=name, description=description)
+        self.dtype = dtype
+        # TODO where and when should this be set?
+        self.metaOf = _metas[dtype]
+
+    def validate(self, value):
+        if value is None:
+            return None
+        cast = self.dtype(value)
+        if not isinstance(value, basestring):
+            assert cast == value, \
+                "Lost information converting %s to %s" % (value, cast)
+        return cast
+
+    def to_dict(self):
+        d = super(NumberMeta, self).to_dict()
+        return d
+
+    @classmethod
+    def from_dict(self, name, d, *args):
+        number_meta = NumberMeta(name, d["description"], *args)
+        return number_meta

tests/test_core/test_numbermeta.py

@@ -0,0 +1,60 @@
+import sys
+import os
+import unittest
+from collections import OrderedDict
+sys.path.append(os.path.join(os.path.dirname(__file__), "..", ".."))
+
+from pkg_resources import require
+require("numpy")
+import numpy as np
+
+from malcolm.core.numbermeta import NumberMeta
+from malcolm.core.attributemeta import AttributeMeta
+
+class TestNumberMeta(unittest.TestCase):
+    def test_init_int(self):
+        nm = NumberMeta("nm", "desc", np.int32)
+        self.assertEqual(nm.metaOf, "malcolm:core/Int:1.0")
+
+    def test_init_float(self):
+        nm = NumberMeta("nm", "desc", np.float64)
+        self.assertEqual(nm.metaOf, "malcolm:core/Float:1.0")
+
+    def test_to_dict(self):
+        nm = NumberMeta("nm", "desc", np.float64)
+        expected = OrderedDict()
+        expected["description"] = "desc"
+        expected["metaOf"] = "malcolm:core/Float:1.0"
+
+        self.assertEqual(expected, nm.to_dict())
+
+    def test_from_dict(self):
+        d = {"description":"desc", "metaOf":"malcolm:core/Float:1.0"}
+        nm = AttributeMeta.from_dict("nm", d)
+        self.assertEqual(NumberMeta, type(nm))
+        self.assertEqual("nm", nm.name)
+        self.assertEqual(np.float64, nm.dtype)
+
+class TestNumberMetaValidation(unittest.TestCase):
+    def test_float_against_float(self):
+        nm = NumberMeta("nm", "desc", np.float64)
+        self.assertEqual(123.456, nm.validate(123.456))
+
+    def test_int_against_float(self):
+        nm = NumberMeta("nm", "desc", np.float64)
+        self.assertEqual(123, nm.validate(123))
+
+    def test_int_against_int(self):
+        nm = NumberMeta("nm", "desc", np.int32)
+        self.assertEqual(123, nm.validate(123))
+
+    def test_float_fails_against_int(self):
+        nm = NumberMeta("nm", "desc", np.int32)
+        self.assertRaises(AssertionError, nm.validate, 123.456)
+
+    def test_none_validates(self):
+        nm = NumberMeta("nm", "desc", np.int32)
+        self.assertIsNone(nm.validate(None))
+
+if __name__ == "__main__":
+    unittest.main(verbosity=2)