diff options
Diffstat (limited to 'scss/types.py')
| -rw-r--r-- | scss/types.py | 17 |
1 files changed, 16 insertions, 1 deletions
diff --git a/scss/types.py b/scss/types.py index e733377..c35905a 100644 --- a/scss/types.py +++ b/scss/types.py @@ -5,6 +5,7 @@ from __future__ import unicode_literals from collections import Iterable import colorsys +from fractions import Fraction import operator import re import string @@ -255,7 +256,21 @@ class Number(Value): self.unit_denom = amount.unit_denom return - if not isinstance(amount, (int, float)): + # Numbers with units are stored internally as a "base" unit, which can + # involve float division, which can lead to precision errors in obscure + # cases. Storing the original units would only partially solve this + # problem, because there'd still be a possible loss of precision when + # converting in Sass-land. Almost all of the conversion factors are + # simple ratios of small whole numbers, so using Fraction across the + # board preserves as much precision as possible. + # TODO in fact, i wouldn't mind parsing Sass values as fractions of a + # power of ten! + # TODO this slowed the test suite down by about 10%, ha + if isinstance(amount, (int, float)): + amount = Fraction.from_float(amount) + elif isinstance(amount, Fraction): + pass + else: raise TypeError("Expected number, got %r" % (amount,)) if unit is not None: |