ignore additional keyword arguments in python [duplicate]

5 days ago Fair enough. However, is there anyway to, in the definition of f or in the calling of it, tell Python to just ignore any keys that are not parameter names? Preferable a method that allows defaults to be specified. Answer. As an extension to the answer posted by @Bas, I would suggest to add the kwargs arguments (variable length keyword arguments) as the second parameter to the … , But Python 3’s sorted function requires all arguments after the provided iterable to be specified as keyword arguments: Keyword arguments come up quite a bit in Python’s built-in functions as well as in the standard library and third party libraries. , 1 week ago Apr 22, 2006  · Abstract. This PEP proposes a change to the way that function arguments are assigned to named parameter slots. In particular, it enables the declaration of “keyword-only” arguments: arguments that can only be supplied by keyword and which will never be automatically filled in by a positional argument. , An arguments position often doesn’t convey as much meaning as its name. So when calling functions, consider naming arguments that you pass in if it might make their meaning clearer. When defining a new function, stop to think about which arguments should always be specified as keyword arguments when calling your function.

def foo(x): ...

def foo(x, ** kw): #...

class Test(object): def __init__(self, id, name): self.id = id self.name = name def foo(d): return Test( ** d) # this works well d = {
         'id': 'aaa',
         'name': 'aaa-name'｝
         foo(d) # this would not work well,
         because of parameter variations,
         a external paraadd into dict d.d = {
            'id': 'aaa',
            'name': 'aaa-name',
            'test1': 'test1'｝
            # traceback TypeError: __init__() got an unexpected keyword argument 'test1'

class Test(object): def __init__(self, id, name, ** kwargs): self.id = id self.name = name

class Test(object): def __init__(self, id, name, ** kwargs): self.id = id self.name = name self.__dict__.update(kwargs)

In[2]: class Test(object): def __init__(self, id, name, ** kwargs): self.id = id self.name = name self.__dict__.update(kwargs) In[3]: d = {
   'id': 'aaa',
   'name': 'aaa-name',
   'test1': 'test1'
}
In[5]: t = Test( ** d) In[6]: t.id Out[5]: 'aaa'
In[7]: t.name Out[6]: 'aaa-name'
In[8]: t.test1 Out[7]: 'test1'

Keyword arguments are not mandatory and have default values. They are often used for optional parameters sent to the function. When a function has more than two or three positional parameters, its signature is more difficult to remember and using keyword arguments with default values is helpful. For instance, a more complete send function could be defined as send(message, to, cc=None, bcc=None). Here cc and bcc are optional, and evaluate to None when they are not passed another value.,Positional arguments are mandatory and have no default values. They are the simplest form of arguments and they can be used for the few function arguments that are fully part of the function’s meaning and their order is natural. For instance, in send(message, recipient) or point(x, y) the user of the function has no difficulty remembering that those two functions require two arguments, and in which order.,It is up to the programmer writing the function to determine which arguments are positional arguments and which are optional keyword arguments, and to decide whether to use the advanced techniques of arbitrary argument passing. If the advice above is followed wisely, it is possible and enjoyable to write Python functions that are:,As a side note, following YAGNI principle, it is often harder to remove an optional argument (and its logic inside the function) that was added “just in case” and is seemingly never used, than to add a new optional argument and its logic when needed.

def make_complex( * args):
   x, y = args
return dict( ** locals())

def make_complex(x, y):
   return {
      'x': x,
      'y': y
   }

print 'one'; print 'two'

if x == 1: print 'one'

if <complex comparison> and <other complex comparison>:
      # do something

print 'one'
print 'two'

if x == 1:
print 'one'

cond1 = <complex comparison>
   cond2 = <other complex comparison>
      if cond1 and cond2:
      # do something

def complex_function(a, b, c):
   if not a:
   return None # Raising an exception might be better
if not b:
   return None # Raising an exception might be better
# Some complex code trying to compute x from a, b and c
# Resist temptation to
return x
if succeeded
if not x:
   # Some Plan - B computation of x
return x # One single exit point
for the returned value x will help
# when maintaining the code.

for index, item in enumerate(some_list):
   # do something with index and item

If the class already defines __init__(), this parameter is ignored.,init: If true (the default), a __init__() method will be generated. If the class already defines __init__(), this parameter is ignored. ,If the class already defines __eq__(), this parameter is ignored.,If the class already defines __repr__(), this parameter is ignored.

from dataclasses
import dataclass

@dataclass
class InventoryItem:
   ""
"Class for keeping track of an item in inventory."
""
name: str
unit_price: float
quantity_on_hand: int = 0

def total_cost(self) - > float:
   return self.unit_price * self.quantity_on_hand

def __init__(self, name: str, unit_price: float, quantity_on_hand: int = 0):
   self.name = name
self.unit_price = unit_price
self.quantity_on_hand = quantity_on_hand

@dataclass
class C:
   ...

   @dataclass()
class C:
   ...

   @dataclass(init = True, repr = True, eq = True, order = False, unsafe_hash = False, frozen = False, match_args = True, kw_only = False, slots = False)
class C:
   ...

@dataclass
class C:
   a: int # 'a'
has no
default value
b: int = 0 # assign a
default value
for 'b'

def __init__(self, a: int, b: int = 0):

@dataclass
class C:
   mylist: list[int] = field(default_factory = list)

c = C()
c.mylist += [1, 2, 3]