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I just started learning Python, what does this syntax mean? **json.loads(my_json)) from with_slots = [get_size(MyUserWithSlots(**json.loads(my_json))

• vtbassmatt 9y ago
  This uses the key-value pairs as keyword arguments.
• jedberg 9y ago
  Unpacks the object into a dictionary. It's syntactic sugar: https://stackoverflow.com/a/2921893/66202 https://stackoverflow.com/a/2921893/66202
• deathanatos 9y ago
  A function in Python takes two kinds of arguments: positional arguments, and keyword arguments. def foo(a, b, c): pass # Arguments passed positionally: foo(1, 2, 3) # or passed by keyword: foo(a=1, b=2, c=3) Now, say you want to make that second call somewhat dynamically, and you have the dict: a_dict = {'a': 1, 'b': 2, 'c': 3} You can make that second foo call: foo(**a_dict) # because of the value of a_dict, expands to: # foo(a=1, b=2, c=3) Functions themselves can take only positional arguments, only keyword arguments, or really, any combination of them. Here is a decent SO question and answer[1] that might help, a bit about it in the tutorial[2], and last, the formal documentation[3]. [1]: https://stackoverflow.com/questions/1419046/python-normal-arguments-vs-keyword-arguments https://stackoverflow.com/questions/1419046/python-normal-ar... [2]: https://docs.python.org/2/tutorial/controlflow.html#keyword-arguments https://docs.python.org/2/tutorial/controlflow.html#keyword-... [3]: https://docs.python.org/2/reference/expressions.html#grammar-token-call https://docs.python.org/2/reference/expressions.html#grammar...
  • spraak 9y ago
    Awesome, thank you for the detailed explanation!