filters.py 文件源码

def make_attrgetter(environment, attribute):
    """Returns a callable that looks up the given attribute from a
    passed object with the rules of the environment.  Dots are allowed
    to access attributes of attributes.  Integer parts in paths are
    looked up as integers.
    """
    if not isinstance(attribute, string_types) \
       or ('.' not in attribute and not attribute.isdigit()):
        return lambda x: environment.getitem(x, attribute)
    attribute = attribute.split('.')
    def attrgetter(item):
        for part in attribute:
            if part.isdigit():
                part = int(part)
            item = environment.getitem(item, part)
        return item
    return attrgetter