kwargs

问题 I am using Django's pre_save signal to implement auto_now_add. There is a lot of discussion on the internet on why you should or shouldn't implement it yourself. I do not appreciate comments on this. Neither on whether I should be rewriting the save function (I have a lot of models that use auto_now_add so using signals makes sense). My question is: I would like to check if the instance is created or updated. According to some sources on the internet this can be done by testing if kwargs[

问题 I'd like to do something like this: class A(object): def __init__(self, **kwargs): """ return exception if certain arguments not set """ class B(A): def __init__(self, **kwargs): super(B, self).__init__(**kwargs) Basically, each subclass will require certain arguments to be properly instantiated. They are the same params across the board. I only want to do the checking of these arguments once. If I can do this from the parent init () - all the better. Is it possible to do this? 回答1: Sure.

问题 I'd like to do something like this: class A(object): def __init__(self, **kwargs): """ return exception if certain arguments not set """ class B(A): def __init__(self, **kwargs): super(B, self).__init__(**kwargs) Basically, each subclass will require certain arguments to be properly instantiated. They are the same params across the board. I only want to do the checking of these arguments once. If I can do this from the parent init () - all the better. Is it possible to do this? 回答1: Sure.

问题 this is my first time posting here. hopefully i can get nice advice:) i have learnt how to pass both **kwargs and *args into a function, and it worked pretty well. like the following: def market_prices(name, **kwargs): print("Hello! Welcome to "+name+" Market!") for fruit, price in kwargs.items(): price_list = " {} is NTD {} per piece.".format(fruit,price) print (price_list) market_prices('Wellcome',banana=8, apple=10) however in real case, i'd rather pre-defined a dictionary with lots of key

问题 def func(**kwargs): for key, value in kwargs.items(): # Is key always going to be a string? # Could it have spaces? pass Hey Guys, Two questions about kwargs in Python. Is every key of kwargs guaranteed to be of type str? If so, I can avoid type checking. If #1 is true, would every key be guaranteed to not have spaces? Thanks, 回答1: A keyword argument passed directly must be a valid Python identifier, and yes it will always be treated as strings. Anything else is a SyntaxError . f(foo=1) #

问题 I am building a simple social network in django. In the "home" of my social, I have the list of all posts published by all users, with author and publishing date. The publishing date have a link to a url that should return the detail view of a specific post published by a user. However, as I click on it, it shows me the list of all posts published by its author (this also works when I click on the author link of the post). So both www.mysocial.com/posts/by/ciccio/7/ and www.mysocial.com/posts

问题 Following this question, I want to make my question as specific as possible focusing on the part that I can not solve. Consider a very simple function of: def foo(x, y, a, b, c): return a * x**4 + b * y**2 + c now I want to use the scipy.optimize.minimize or any of other existing functions to find the x and y (i.e., parameters) to minimize foo given the constants a , b , and c (i.e., args). If I had only one parameter and multiples arguments then from this page I could do: def foo(x, *args):

问题 I have the following: class Foo: def __init__(self, **kwargs): print kwargs settings = {foo:"bar"} f = Foo(settings) This generates an error: Traceback (most recent call last): File "example.py", line 12, in <module> settings = {foo:"bar"} NameError: name 'foo' is not defined How do I properly pass a dict of key/value args to kwargs? 回答1: Use the **kw call convention: f = Foo(**settings) This works on any callable that takes keyword arguments: def foo(spam='eggs', bar=None): return spam, bar

问题 I have the following: class Foo: def __init__(self, **kwargs): print kwargs settings = {foo:"bar"} f = Foo(settings) This generates an error: Traceback (most recent call last): File "example.py", line 12, in <module> settings = {foo:"bar"} NameError: name 'foo' is not defined How do I properly pass a dict of key/value args to kwargs? 回答1: Use the **kw call convention: f = Foo(**settings) This works on any callable that takes keyword arguments: def foo(spam='eggs', bar=None): return spam, bar

问题 I have the following: class Foo: def __init__(self, **kwargs): print kwargs settings = {foo:"bar"} f = Foo(settings) This generates an error: Traceback (most recent call last): File "example.py", line 12, in <module> settings = {foo:"bar"} NameError: name 'foo' is not defined How do I properly pass a dict of key/value args to kwargs? 回答1: Use the **kw call convention: f = Foo(**settings) This works on any callable that takes keyword arguments: def foo(spam='eggs', bar=None): return spam, bar