def __init__(self, default=REQUIRED, pattern=None):
        super(String, self).__init__(default)
        self.pattern = pattern
        if pattern:
            self.regex = re.compile(pattern)
Calculates and returns the ID attribute for this BoundField, if the
dataset/ETHPy150Open beetbox/beets/beets/util/confit.py/String.__init__--crossover with--dataset/ETHPy150Open AppScale/appscale/AppServer/lib/django-0.96/django/newforms/forms.py/BoundField._auto_id