*Memo:
- My post explains a function.
- My post explains positional-only parameters in a function.
- My post explains keyword-only parameters in a function.
- My post explains positional-only parameters and keyword-only parameters together in a function.
Parameters can be set to a function definition as shown below:
*Memo:
- The basic parameter is called the positional-or-keyword parameter which accepts a positional or keyword argument from a function call:
- The doc officially says positional-or-keyword arguments but they're actually positional-or-keyword parameters.
- A parameter can have or doesn't need to have a default value:
- The parameter which has a default value is the required parameter which must get an argument from a function call. *E.g.
def func(p='Hello'): pass. - The parameter which doesn't have a default value is the optional parameter which can get or doesn't need to get an argument from a function call. *E.g.
def func(p): pass.
- The parameter which has a default value is the required parameter which must get an argument from a function call. *E.g.
- All the parameters after a required parameter must be required parameters.
- There cannot be multiple same name parameters.
def func(fname, lname, age, gender): pass def func(fname="John", lname="Smith", age=36, gender="Male"): pass def func(fname, lname, age=36, gender="Male"): pass # No error def func(fname="John", lname="Smith", 36, "Male"): pass # SyntaxError: invalid syntax def func(fname, lname, age, gender, lname): pass # SyntaxError: duplicate argument 'lname' in function definition Arguments can be set to a function call to be passed to a function as shown below:
*Memo:
- There are a positional argument(
"John") and keyword argument(fname="John"):- A positional argument cares its position to be passed to the corresponding parameter position because it cannot specify a parameter with a parameter name.
- A keyword argument doesn't care its position to be passed to the corresponding parameter position because it can specify a parameter with a parameter name.
- All the arguments after a keyword argument must be keyword arguments.
- There cannot be multiple values for one parameter.
- There cannot be multiple same name keyword arguments.
def func(fname, lname, age, gender): print(fname, lname, age, gender) func("John", "Smith", 36, "Male") func(fname="John", lname="Smith", age=36, gender="Male") func(**{"fname":"John", "lname":"Smith", "age":36, "gender":"Male"}) func(age=36, lname="Smith", gender="Male", fname="John") func(**{"age":36, "lname":"Smith", "gender":"Male", "fname":"John"}) func("John", "Smith", age=36, gender="Male") func("John", "Smith", **{"age":36, "gender":"Male"}) # John Smith 36 Male func(fname="John", lname="Smith", 36, "Male") # SyntaxError: positional argument follows keyword argument func(36, "Smith", age=36, fname="John") # TypeError: func() got multiple values for argument 'fname' func(lname="Smith", lname="Brown", age=36, gender="Male") # SyntaxError: keyword argument repeated: lname def func(fname="John", lname="Smith", age=36, gender="Male"): print(fname, lname, age, gender) func() # John Smith 36 Male func("Tom", "Brown") # Tom Brown 36 Male func(fname="Anna", gender="Female") func(**{"fname":"Anna", "gender":"Female"}) func(gender="Female", fname="Anna") func(**{"gender":"Female", "fname":"Anna"}) # Anna Smith 36 Female func("Anna", "Brown", age=27, gender="Female") func("Anna", "Brown", **{"age":27, "gender":"Female"}) func("Anna", "Brown", gender="Female", age=27) func("Anna", "Brown", **{"gender":"Female", "age":27}) # Anna Brown 27 Female 
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