Parámetros especiales en funciones

#
#
def standard_arg(arg):
    print(arg)

standard_arg(1)

1

standard_arg(arg=1)

1

#
# Unicamente posicional
#
def pos_only_arg(arg, /):
    print(arg)

pos_only_arg(1)

1

pos_only_arg(pos=1)

---------------------------------------------------------------------------
TypeError                                 Traceback (most recent call last)
Cell In[7], line 1
----> 1 pos_only_arg(pos=1)

TypeError: pos_only_arg() got an unexpected keyword argument 'pos'

#
# Unicamente con nombre
#
def kwd_only_arg(*, arg):
    print(arg)

kwd_only_arg(arg=1)

1

kwd_only_arg(1)

---------------------------------------------------------------------------
TypeError                                 Traceback (most recent call last)
Cell In[11], line 1
----> 1 kwd_only_arg(1)

TypeError: kwd_only_arg() takes 0 positional arguments but 1 was given

#
# Parámetros combinados
#
def combined_example(pos_only, /, standard, *, kwd_only):
    print(pos_only, standard, kwd_only)

combined_example(1, 2, kwd_only=3)

1 2 3

combined_example(1, standard=2, kwd_only=3)

1 2 3

combined_example(1, 2, 3)

---------------------------------------------------------------------------
TypeError                                 Traceback (most recent call last)
Cell In[15], line 1
----> 1 combined_example(1, 2, 3)

TypeError: combined_example() takes 2 positional arguments but 3 were given

combined_example(pos_only=1, standard=2, kwd_only=3)

---------------------------------------------------------------------------
TypeError                                 Traceback (most recent call last)
Cell In[16], line 1
----> 1 combined_example(pos_only=1, standard=2, kwd_only=3)

TypeError: combined_example() got some positional-only arguments passed as keyword arguments: 'pos_only'

#
# Colisiones
#
def foo(name, **kwds):
    return 'name' in kwds

foo(1, **{'name': 2})

---------------------------------------------------------------------------
TypeError                                 Traceback (most recent call last)
Cell In[18], line 1
----> 1 foo(1, **{'name': 2})

TypeError: foo() got multiple values for argument 'name'

#
# Uso con posicionales
#
def foo(name, /, **kwds):
    return 'name' in kwds

foo(1, **{'name': 2})