PYTHON

python override inherited method

import datetime

class Logger(object):
    def log(self, message):
        print message

class TimestampLogger(Logger):
    def log(self, message):
        message = "{ts} {msg}".format(ts=datetime.datetime.now().isoformat(),
                                      msg=message)
        super(TimestampLogger, self).log(message)

python override inherited method class model constructor

class Parent(object):
    def __init__(self, a, b):
        print 'a', a
        print 'b', b

class Child(Parent):
    def __init__(self, c, d, *args, **kwargs):
        print 'c', c
        print 'd', d
        super(Child, self).__init__(*args, **kwargs)

test = Child(1,2,3,4)

python override inherited method class model constructor

class Bar(object):
   def __init__(self, arg1=None, arg2=None, argN=None):
       print arg1, arg2, argN

class Foo(Bar):
    def __init__(self, my_new_arg=None, **kwds):
       super(Foo, self).__init__(**kwds)
       self.new_arg = my_new_arg
       print my_new_arg

f = Foo(my_new_arg='x', arg2='y')

python override inherited method data model constructor

class Parent:
    def __init__(self, common, data, **kwargs):
        super().__init__(**kwargs)
        self.common = common
        self.data = data

    @classmethod
    def from_file(cls, filename, **kwargs):
        # If the caller provided a data argument,
        # ignore it and use the data from the file instead.
        kwargs['data'] = load_data(filename)
        return cls(**kwargs)

    @classmethod
    def from_directory(cls, data_dir, **kwargs):
        return [cls.from_file(data_file, **kwargs)
                for data_file in get_data_files(data_dir)]
        

class ChildA(Parent):
    def __init__(self, specific, **kwargs):
        super().__init__(**kwargs)
        self.specific = specific