Transform decimal precision getter into a free function.

babel/numbers.py

@@ -319,6 +319,19 @@ def format_number(number, locale=LC_NUMERIC):
     return format_decimal(number, locale=locale)
 
 
+def get_decimal_precision(number):
+    """Return maximum precision of a decimal instance's fractional part.
+
+    Precision is extracted from the fractional part only.
+    """
+    # Copied from: https://github.com/mahmoud/boltons/pull/59
+    assert isinstance(number, decimal.Decimal)
+    decimal_tuple = number.normalize().as_tuple()
+    if decimal_tuple.exponent >= 0:
+        return 0
+    return abs(decimal_tuple.exponent)
+
+
 def format_decimal(
         number, format=None, locale=LC_NUMERIC,
         decimal_quantization=True):
@@ -717,18 +730,6 @@ def compute_scale(self):
             scale = 3
         return scale
 
-    @staticmethod
-    def precision(number):
-        """Return maximum precision of a decimal instance's fractional part.
-
-        Precision is extracted from the fractional part only.
-        """
-        # Copied from: https://github.com/mahmoud/boltons/pull/59
-        decimal_tuple = number.normalize().as_tuple()
-        if decimal_tuple.exponent >= 0:
-            return 0
-        return abs(decimal_tuple.exponent)
-
     @staticmethod
     def quantum(precision):
         """Return minimal quantum of a number, as defined by precision."""
@@ -785,7 +786,7 @@ def apply(
         # Bump decimal precision to the natural precision of the number if it
         # exceeds the one we're about to use.
         if not decimal_quantization:
-            frac_prec = (frac_prec[0], max([frac_prec[1], self.precision(value)]))
+            frac_prec = (frac_prec[0], max([frac_prec[1], get_decimal_precision(value)]))
 
         # Render scientific notation.
         if self.exp_prec: