Issue #15783: Except for the number methods, the C version of decimal now

supports all None default values present in decimal.py. These values were
largely undocumented.

Lib/decimal.py

@@ -2596,7 +2596,7 @@ class Decimal(object):
         ans = ans._fix(context)
         return ans
 
-    def same_quantum(self, other):
+    def same_quantum(self, other, context=None):
         """Return True if self and other have the same exponent; otherwise
         return False.
 
@@ -2914,7 +2914,7 @@ class Decimal(object):
         except TypeError:
             return 0
 
-    def canonical(self, context=None):
+    def canonical(self):
         """Returns the same Decimal object.
 
         As we do not have different encodings for the same number, the
@@ -2934,7 +2934,7 @@ class Decimal(object):
             return ans
         return self.compare(other, context=context)
 
-    def compare_total(self, other):
+    def compare_total(self, other, context=None):
         """Compares self to other using the abstract representations.
 
         This is not like the standard compare, which use their numerical
@@ -3007,7 +3007,7 @@ class Decimal(object):
         return _Zero
 
 
-    def compare_total_mag(self, other):
+    def compare_total_mag(self, other, context=None):
         """Compares self to other using abstract repr., ignoring sign.
 
         Like compare_total, but with operand's sign ignored and assumed to be 0.
@@ -3029,7 +3029,7 @@ class Decimal(object):
         else:
             return _dec_from_triple(1, self._int, self._exp, self._is_special)
 
-    def copy_sign(self, other):
+    def copy_sign(self, other, context=None):
         """Returns self with the sign of other."""
         other = _convert_other(other, raiseit=True)
         return _dec_from_triple(other._sign, self._int,
@@ -4182,7 +4182,7 @@ class Context(object):
         """
         if not isinstance(a, Decimal):
             raise TypeError("canonical requires a Decimal as an argument.")
-        return a.canonical(context=self)
+        return a.canonical()
 
     def compare(self, a, b):
         """Compares values numerically.

Misc/NEWS

@@ -108,6 +108,10 @@ Core and Builtins
 Library
 -------
 
+- Issue #15783: Except for the number methods, the C version of decimal now
+  supports all None default values present in decimal.py. These values were
+  largely undocumented.
+
 - Issue #16298: In HTTPResponse.read(), close the socket when there is no
   Content-Length and the incoming stream is finished.  Patch by Eran
   Rundstein.

Modules/_decimal/tests/deccheck.py

@@ -36,6 +36,7 @@ from copy import copy
 from collections import defaultdict
 from test.support import import_fresh_module
 from randdec import randfloat, all_unary, all_binary, all_ternary
+from randdec import unary_optarg, binary_optarg, ternary_optarg
 from formathelper import rand_format, rand_locale
 
 C = import_fresh_module('decimal', fresh=['_decimal'])
@@ -834,6 +835,17 @@ def test_unary(method, prec, exp_range, restricted_range, itr, stat):
         except VerifyError as err:
             log(err)
 
+    if not method.startswith('__'):
+        for op in unary_optarg(prec, exp_range, itr):
+            t = TestSet(method, op)
+            try:
+                if not convert(t):
+                    continue
+                callfuncs(t)
+                verify(t, stat)
+            except VerifyError as err:
+                log(err)
+
 def test_binary(method, prec, exp_range, restricted_range, itr, stat):
     """Iterate a binary function through many test cases."""
     if method in BinaryRestricted:
@@ -848,6 +860,17 @@ def test_binary(method, prec, exp_range, restricted_range, itr, stat):
         except VerifyError as err:
             log(err)
 
+    if not method.startswith('__'):
+        for op in binary_optarg(prec, exp_range, itr):
+            t = TestSet(method, op)
+            try:
+                if not convert(t):
+                    continue
+                callfuncs(t)
+                verify(t, stat)
+            except VerifyError as err:
+                log(err)
+
 def test_ternary(method, prec, exp_range, restricted_range, itr, stat):
     """Iterate a ternary function through many test cases."""
     if method in TernaryRestricted:
@@ -862,6 +885,17 @@ def test_ternary(method, prec, exp_range, restricted_range, itr, stat):
         except VerifyError as err:
             log(err)
 
+    if not method.startswith('__'):
+        for op in ternary_optarg(prec, exp_range, itr):
+            t = TestSet(method, op)
+            try:
+                if not convert(t):
+                    continue
+                callfuncs(t)
+                verify(t, stat)
+            except VerifyError as err:
+                log(err)
+
 def test_format(method, prec, exp_range, restricted_range, itr, stat):
     """Iterate the __format__ method through many test cases."""
     for op in all_unary(prec, exp_range, itr):

Modules/_decimal/tests/randdec.py

@@ -527,6 +527,11 @@ def all_unary(prec, exp_range, itr):
     for _ in range(100):
         yield (randtuple(prec, exp_range),)
 
+def unary_optarg(prec, exp_range, itr):
+    for _ in range(100):
+        yield randdec(prec, exp_range), None
+        yield randdec(prec, exp_range), None, None
+
 def all_binary(prec, exp_range, itr):
     for a, b in bin_close_to_pow10(prec, exp_range, itr):
         yield a, b
@@ -543,6 +548,11 @@ def all_binary(prec, exp_range, itr):
     for _ in range(100):
         yield randdec(prec, exp_range), randdec(prec, exp_range)
 
+def binary_optarg(prec, exp_range, itr):
+    for _ in range(100):
+        yield randdec(prec, exp_range), randdec(prec, exp_range), None
+        yield randdec(prec, exp_range), randdec(prec, exp_range), None, None
+
 def all_ternary(prec, exp_range, itr):
     for a, b, c in tern_close_numbers(prec, exp_range, -exp_range, itr):
         yield a, b, c
@@ -557,3 +567,11 @@ def all_ternary(prec, exp_range, itr):
         b = randdec(prec, 2*exp_range)
         c = randdec(prec, 2*exp_range)
         yield a, b, c
+
+def ternary_optarg(prec, exp_range, itr):
+    for _ in range(100):
+        a = randdec(prec, 2*exp_range)
+        b = randdec(prec, 2*exp_range)
+        c = randdec(prec, 2*exp_range)
+        yield a, b, c, None
+        yield a, b, c, None, None