Simplify the selection of decimal implementation

Instead of selecting individual symbols, expose only the chosen decimal module
through babel._compat.  This forces Babel to always use "decimal." prefix.
Howver, it will simplify the code for users that need to manipulate the decimal
context.

4 files changed, 22 insertions, 24 deletions

diff --git a/babel/_compat.py b/babel/_compat.py
index ae290f4..aea3389 100644
--- a/babel/_compat.py
+++ b/babel/_compat.py
@@ -58,15 +58,13 @@ number_types = integer_types + (float,)
 
 
 #
-# Use cdecimal when available
+# Since Python 3.3, a fast decimal implementation is already included in the
+# standard library.  Otherwise use cdecimal when available
 #
-from decimal import (Decimal as _dec,
-                     InvalidOperation as _invop)
-try:
-    from cdecimal import (Decimal as _cdec,
-                          InvalidOperation as _cinvop)
-    Decimal = _cdec
-    InvalidOperation = (_invop, _cinvop)
-except ImportError:
-    Decimal = _dec
-    InvalidOperation = _invop
+if sys.version_info[:2] >= (3, 3):
+    import decimal
+else:
+    try:
+        import cdecimal as decimal
+    except ImportError:
+        import decimal
diff --git a/babel/numbers.py b/babel/numbers.py
index 67881ae..f9be88d 100644
--- a/babel/numbers.py
+++ b/babel/numbers.py
@@ -22,7 +22,7 @@ import re
 from datetime import date as date_, datetime as datetime_
 
 from babel.core import default_locale, Locale, get_global
-from babel._compat import Decimal, InvalidOperation
+from babel._compat import decimal
 
 
 LC_NUMERIC = default_locale('LC_NUMERIC')
@@ -437,9 +437,9 @@ def parse_decimal(string, locale=LC_NUMERIC):
     """
     locale = Locale.parse(locale)
     try:
-        return Decimal(string.replace(get_group_symbol(locale), '')
-                       .replace(get_decimal_symbol(locale), '.'))
-    except InvalidOperation:
+        return decimal.Decimal(string.replace(get_group_symbol(locale), '')
+                               .replace(get_decimal_symbol(locale), '.'))
+    except decimal.InvalidOperation:
         raise NumberFormatError('%r is not a valid decimal number' % string)
 
 
@@ -566,8 +566,8 @@ class NumberPattern(object):
 
     def apply(self, value, locale, currency=None, force_frac=None):
         frac_prec = force_frac or self.frac_prec
-        if not isinstance(value, Decimal):
-            value = Decimal(str(value))
+        if not isinstance(value, decimal.Decimal):
+            value = decimal.Decimal(str(value))
         value = value.scaleb(self.scale)
         is_negative = int(value.is_signed())
         if self.exp_prec:  # Scientific notation
@@ -603,7 +603,7 @@ class NumberPattern(object):
             if sep:
                 number += get_decimal_symbol(locale) + b
         else:  # A normal number pattern
-            precision = Decimal('1.' + '1' * frac_prec[1])
+            precision = decimal.Decimal('1.' + '1' * frac_prec[1])
             rounded = value.quantize(precision)
             a, sep, b = str(abs(rounded)).partition(".")
             number = (self._format_int(a, self.int_prec[0],
@@ -641,7 +641,7 @@ class NumberPattern(object):
     def _format_significant(self, value, minimum, maximum):
         exp = value.adjusted()
         scale = maximum - 1 - exp
-        digits = str(value.scaleb(scale).quantize(Decimal(1)))
+        digits = str(value.scaleb(scale).quantize(decimal.Decimal(1)))
         if scale <= 0:
             result = digits + '0' * -scale
         else:
diff --git a/babel/plural.py b/babel/plural.py
index 980629d..0b8e425 100644
--- a/babel/plural.py
+++ b/babel/plural.py
@@ -11,7 +11,7 @@
 import re
 import sys
 
-from babel._compat import Decimal
+from babel._compat import decimal
 
 
 _plural_tags = ('zero', 'one', 'two', 'few', 'many', 'other')
@@ -33,9 +33,9 @@ def extract_operands(source):
             # 2.6's Decimal cannot convert from float directly
             if sys.version_info < (2, 7):
                 n = str(n)
-            n = Decimal(n)
+            n = decimal.Decimal(n)
 
-    if isinstance(n, Decimal):
+    if isinstance(n, decimal.Decimal):
         dec_tuple = n.as_tuple()
         exp = dec_tuple.exponent
         fraction_digits = dec_tuple.digits[exp:] if exp < 0 else ()
diff --git a/babel/units.py b/babel/units.py
index 798ade2..1ea5b17 100644
--- a/babel/units.py
+++ b/babel/units.py
@@ -80,8 +80,8 @@ def format_unit(value, measurement_unit, length='long', format=None, locale=LC_N
 
     Number formats may be overridden with the ``format`` parameter.
 
-    >>> from babel._compat import Decimal
-    >>> format_unit(Decimal("-42.774"), 'temperature-celsius', 'short', format='#.0', locale='fr')
+    >>> from babel._compat import decimal
+    >>> format_unit(decimal.Decimal("-42.774"), 'temperature-celsius', 'short', format='#.0', locale='fr')
     u'-42,8 \\xb0C'
 
     The locale's usual pluralization rules are respected.