diff options
Diffstat (limited to 'src/pyexiv2.py')
| -rw-r--r-- | src/pyexiv2.py | 42 |
1 files changed, 22 insertions, 20 deletions
diff --git a/src/pyexiv2.py b/src/pyexiv2.py index 0241914..4f23757 100644 --- a/src/pyexiv2.py +++ b/src/pyexiv2.py @@ -289,6 +289,8 @@ class Rational(object): A class representing a rational number. """ + _format_re = re.compile(r'(?P<numerator>-?\d+)/(?P<denominator>\d+)') + def __init__(self, numerator, denominator): """ Constructor. @@ -306,6 +308,26 @@ class Rational(object): self.numerator = long(numerator) self.denominator = long(denominator) + @staticmethod + def from_string(string): + """ + Instantiate a Rational from a string formatted as + C{[-]numerator/denominator}. + + @param string: a string representation of a rational number + @type string: C{str} + + @return: the rational number parsed + @rtype: L{Rational} + + @raise ValueError: if the format of the string is invalid + """ + match = Rational._format_re.match(string) + if match is None: + raise ValueError('Invalid format for a rational: %s' % string) + gd = match.groupdict() + return Rational(long(gd['numerator']), long(gd['denominator'])) + def __eq__(self, other): """ Compare two rational numbers for equality. @@ -327,26 +349,6 @@ class Rational(object): """ return '%d/%d' % (self.numerator, self.denominator) -def StringToRational(string): - """ - Try to convert a string containing a rational number to a Rational object. - - Try to convert a string containing a rational number to the corresponding - Rational object. - The conversion is done by matching a regular expression. - If the pattern does not match, the Rational object with numerator=0 and - denominator=1 is returned. - - Keyword arguments: - string -- the string potentially containing a rational number - """ - pattern = re.compile("(-?[0-9]+)/(-?[1-9][0-9]*)") - match = pattern.match(string) - if match == None: - return Rational(0, 1) - else: - return Rational(*map(long, match.groups())) - class MetadataTag(object): |