REF: Undelete keywordonly.py module

Author: rmarkello

nibabel/keywordonly.py

@@ -0,0 +1,28 @@
+""" Decorator for labeling keyword arguments as keyword only
+"""
+
+from functools import wraps
+
+
+def kw_only_func(n):
+    """ Return function decorator enforcing maximum of `n` positional arguments
+    """
+    def decorator(func):
+        @wraps(func)
+        def wrapper(*args, **kwargs):
+            if len(args) > n:
+                raise TypeError(
+                    '{0} takes at most {1} positional argument{2}'.format(
+                        func.__name__, n, 's' if n > 1 else ''))
+            return func(*args, **kwargs)
+        return wrapper
+    return decorator
+
+
+def kw_only_meth(n):
+    """ Return method decorator enforcing maximum of `n` positional arguments
+
+    The method has at least one positional argument ``self`` or ``cls``; allow
+    for that.
+    """
+    return kw_only_func(n + 1)

nibabel/tests/test_keywordonly.py

@@ -0,0 +1,43 @@
+""" Test kw_only decorators """
+
+from ..keywordonly import kw_only_func, kw_only_meth
+
+from nose.tools import assert_equal
+from nose.tools import assert_raises
+
+
+def test_kw_only_func():
+    # Test decorator
+    def func(an_arg):
+        "My docstring"
+        return an_arg
+    assert_equal(func(1), 1)
+    assert_raises(TypeError, func, 1, 2)
+    dec_func = kw_only_func(1)(func)
+    assert_equal(dec_func(1), 1)
+    assert_raises(TypeError, dec_func, 1, 2)
+    assert_raises(TypeError, dec_func, 1, akeyarg=3)
+    assert_equal(dec_func.__doc__, 'My docstring')
+
+    @kw_only_func(1)
+    def kw_func(an_arg, a_kwarg='thing'):
+        "Another docstring"
+        return an_arg, a_kwarg
+    assert_equal(kw_func(1), (1, 'thing'))
+    assert_raises(TypeError, kw_func, 1, 2)
+    assert_equal(kw_func(1, a_kwarg=2), (1, 2))
+    assert_raises(TypeError, kw_func, 1, akeyarg=3)
+    assert_equal(kw_func.__doc__, 'Another docstring')
+
+    class C(object):
+
+        @kw_only_meth(1)
+        def kw_meth(self, an_arg, a_kwarg='thing'):
+            "Method docstring"
+            return an_arg, a_kwarg
+    c = C()
+    assert_equal(c.kw_meth(1), (1, 'thing'))
+    assert_raises(TypeError, c.kw_meth, 1, 2)
+    assert_equal(c.kw_meth(1, a_kwarg=2), (1, 2))
+    assert_raises(TypeError, c.kw_meth, 1, akeyarg=3)
+    assert_equal(c.kw_meth.__doc__, 'Method docstring')