support string comparison (#61)

Author: NoureldinYosri

test/cython/test_with_unit.py

@@ -18,7 +18,7 @@
 import numpy as np
 import pytest
 
-from tunits.core import raw_WithUnit, raw_UnitArray, WithUnit
+from tunits.core import raw_WithUnit, raw_UnitArray, WithUnit, NotTUnitsLikeError
 
 from tunits import UnitMismatchError, ValueArray, Value
 from test.test_utils import frac, conv, val
@@ -85,7 +85,6 @@ def test_abs() -> None:
 
 def test_equality() -> None:
     equivalence_groups: list[list[Any]] = [
-        [""],
         ["other types"],
         [list],
         [None],
@@ -488,21 +487,11 @@ def test_get_item() -> None:
     v = val(2, conv(numer=3, denom=5, exp10=7), mps, kph)
 
     # Wrong kinds of index (unit array, slice).
-    with pytest.raises(TypeError):
+    with pytest.raises(UnitMismatchError):
         _ = u[mps]
-    with pytest.raises(TypeError):
+    with pytest.raises(NotTUnitsLikeError):
         _ = u[1:2]
 
-    # Safety against dimensionless unit ambiguity.
-    _ = u[u]
-    with pytest.raises(TypeError):
-        _ = u[1.0]
-    with pytest.raises(TypeError):
-        _ = u[1.0]
-    with pytest.raises(TypeError):
-        _ = u[1]
-    with pytest.raises(TypeError):
-        _ = u[2 * v / v]
     assert u[v / v] == 10
 
     # Wrong unit.

test/test_value.py

@@ -177,10 +177,7 @@ def test_division() -> None:
 def test_get_item() -> None:
     from tunits.units import ns, s
 
-    with pytest.raises(TypeError):
-        _ = (ns / s)[2 * s / ns]
-    with pytest.raises(TypeError):
-        _ = (ns / s)[Value(3, '')]
+    assert (ns / s)[Value(3, '')] == pytest.approx(1 / 3 * 1e-9)
     assert Value(1, '')[Value(1, '')] == 1
     assert Value(1, '')[ns / s] == 10**9
 

tunits/core/cython/with_unit.pyx

@@ -67,7 +67,13 @@ def _in_WithUnit(obj) -> raw_WithUnit:
     """
     if isinstance(obj, WithUnit):
         return obj
-    return raw_WithUnit(obj, identity_conversion(), _EmptyUnit, _EmptyUnit, Value, ValueArray)
+    try:
+        return raw_WithUnit(obj, identity_conversion(), _EmptyUnit, _EmptyUnit, Value, ValueArray)
+    except NotTUnitsLikeError as e:
+        if isinstance(obj, str):
+            return _try_interpret_as_with_unit(obj)
+        raise e
+
 
 cdef _is_dimensionless_zero(WithUnit u):
     return (u._is_dimensionless() and
@@ -575,6 +581,20 @@ cdef class WithUnit:
             return self.__with_value(self.value[key])
         except NotTUnitsLikeError:
             return NotImplemented
+        except TypeError:
+            try:
+                unit_val = _try_interpret_as_with_unit(str(key), True)
+            except:
+                raise NotTUnitsLikeError("Bad unit key: " + repr(key))
+            if unit_val is None:
+                raise NotTUnitsLikeError("Bad unit key: " + repr(key))
+            if self.base_units != unit_val.base_units:
+                raise UnitMismatchError("'%s' doesn't match '%s'." %
+                    (self, key))
+            return (self.value
+                * conversion_to_double(conversion_div(self.conv, unit_val.conv))
+                / unit_val.value)
+
 
     def __iter__(self):
         # Hack: We want calls to 'iter' to see that __iter__ exists and try to
@@ -688,6 +708,10 @@ cdef class WithUnit:
     def _from_json_dict_(cls, **kwargs):
         return cls(kwargs["value"], kwargs["unit"])
 
+    def _resolved_value_(self) -> WithUnit:
+        """Follows the cirq ResolvableValue protocol."""
+        return self
+
     def __getstate__(self):
         return {
             'value': self.value,