Merge #496

496: Improvements on contribution guidelines, clean up zappr, better System/Group checking and decorator for contexts r=hgrecco

.zappr.yaml

@@ -1,8 +0,0 @@
-approvals:
-  minimum: 1
-  groups:
-    core:
-      minimum: 1
-      from:
-        users:
-          - hgrecco

docs/contributing.rst

@@ -5,23 +5,30 @@ Contributing to Pint
 
 You can contribute in different ways:
 
+
 Report issues
 -------------
 
-You can report any issues with the package, the documentation to the Pint `issue tracker`_. Also feel free to submit feature requests, comments or questions.
+You can report any issues with the package, the documentation to the Pint `issue tracker`_.
+Also feel free to submit feature requests, comments or questions.
 
 
 Contribute code
 ---------------
 
-To contribute fixes, code or documentation to Pint, send us a patch, or fork Pint in github_ and submit the changes using a pull request.
+To contribute fixes, code or documentation to Pint, fork Pint in github_ and submit
+the changes using a pull request against the **master** branch.
 
-If you are contributing **documentation** or **bug fixes**, do it based on the **master** branch.
+- If you are fixing a bug, add a test to test_issues.py
+  Also add "Close #<bug number> as described in the `github docs`_.
+- If you are submitting new code, add tests and documentation.
 
-If you are contributing **new features** or code that changes the behaviour, do it based the **develop** branch.
+Pint uses `bors-ng` as a merge bot and therefore every PR is tested before merging.
 
 In any case, feel free to use the `issue tracker`_ to discuss ideas for new features or improvements.
 
 
 .. _github: http://github.com/hgrecco/pint
 .. _`issue tracker`: https://github.com/hgrecco/pint/issues
+.. _`bors-ng`: https://github.com/bors-ng/bors-ng
+.. _`github docs`: https://help.github.com/articles/closing-issues-via-commit-messages/

pint/default_en.txt

@@ -455,7 +455,7 @@ stere = meter ** 3
     pound
 @end
 
-@system US using USCSLiquidVolume, USCSDryVolume, USCSVolume, USCSLengthInternational, USCSLengthSurvey, AvoirdupoisUS
+@system US using USCSLiquidVolume, USCSDryVolume, USCSVolumeOther, USCSLengthInternational, USCSLengthSurvey, AvoirdupoisUS
     yard
     pound
 @end

pint/registry.py

@@ -35,6 +35,7 @@ from __future__ import division, unicode_literals, print_function, absolute_impo
 import os
 import re
 import math
+import functools
 import itertools
 import pkg_resources
 from decimal import Decimal
@@ -1140,6 +1141,34 @@ class ContextRegistry(BaseRegistry):
             # the added contexts are removed from the active one.
             self.disable_contexts(len(names))
 
+    def with_context(self, name, **kw):
+        """Decorator to wrap a function call in a Pint context.
+
+        Use it to ensure that a certain context is active when
+        calling a function::
+
+            >>> @ureg.with_context('sp')
+            ... def my_cool_fun(wavelenght):
+            ...     print('This wavelength is equivalent to: %s', wavelength.to('terahertz'))
+
+
+        :param names: name of the context.
+        :param kwargs: keyword arguments for the contexts.
+        :return: the wrapped function.
+        """
+        def decorator(func):
+            assigned = tuple(attr for attr in functools.WRAPPER_ASSIGNMENTS if hasattr(func, attr))
+            updated = tuple(attr for attr in functools.WRAPPER_UPDATES if hasattr(func, attr))
+
+            @functools.wraps(func, assigned=assigned, updated=updated)
+            def wrapper(*values, **kwargs):
+                with self.context(name, **kw):
+                    return func(*values, **kwargs)
+
+            return wrapper
+
+        return decorator
+
     def _convert(self, value, src, dst, inplace=False):
         """Convert value from some source to destination units.
 

pint/systems.py

@@ -15,7 +15,7 @@ import re
 
 from .definitions import Definition, UnitDefinition
 from .errors import DefinitionSyntaxError, RedefinitionError
-from .util import to_units_container, SharedRegistryObject, SourceIterator
+from .util import to_units_container, SharedRegistryObject, SourceIterator, logger
 from .babel_names import _babel_systems
 from pint.compat import Loc
 
@@ -309,7 +309,10 @@ class _System(SharedRegistryObject):
             self._computed_members = set()
 
             for group_name in self._used_groups:
-                self._computed_members |= d[group_name].members
+                try:
+                    self._computed_members |= d[group_name].members
+                except KeyError:
+                    logger.warning('Could not resolve {0} in System {1}'.format(group_name, self.name))
 
             self._computed_members = frozenset(self._computed_members)
 

pint/testsuite/test_contexts.py

@@ -5,7 +5,7 @@ from __future__ import division, unicode_literals, print_function, absolute_impo
 import itertools
 from collections import defaultdict
 
-from pint import UnitRegistry
+from pint import UnitRegistry, errors
 from pint.context import Context
 from pint.util import UnitsContainer
 from pint.testsuite import QuantityTestCase
@@ -619,3 +619,41 @@ class TestDefinedContexts(QuantityTestCase):
 
         for a, b in itertools.product(eq, eq):
             self.assertQuantityAlmostEqual(a.to(b.units, 'sp'), b, rtol=0.01)
+
+    def test_decorator(self):
+        ureg = self.ureg
+
+        a = 532. * ureg.nm
+        with ureg.context('sp'):
+            b = a.to('terahertz')
+
+        def f(wl):
+            return wl.to('terahertz')
+
+        self.assertRaises(errors.DimensionalityError, f, a)
+
+        @ureg.with_context('sp')
+        def g(wl):
+            return wl.to('terahertz')
+
+        self.assertEqual(b, g(a))
+
+    def test_decorator_composition(self):
+        ureg = self.ureg
+
+        a = 532. * ureg.nm
+        with ureg.context('sp'):
+            b = a.to('terahertz')
+
+        @ureg.with_context('sp')
+        @ureg.check('[length]')
+        def f(wl):
+            return wl.to('terahertz')
+
+        @ureg.with_context('sp')
+        @ureg.check('[length]')
+        def g(wl):
+            return wl.to('terahertz')
+
+        self.assertEqual(b, f(a))
+        self.assertEqual(b, g(a))

pint/testsuite/test_systems.py

@@ -340,3 +340,8 @@ class TestSystem(QuantityTestCase):
         c = ureg.get_base_units('kph', system=sysname)
         self.assertAlmostEqual(c[0], 0.6213, places=3)
         self.assertEqual(c[1], {'mph': 1})
+
+    def test_members_nowarning(self):
+        ureg = self.ureg
+        for name in dir(ureg.sys):
+            s = dir(getattr(ureg.sys, name))