Python parameter combination, python Parameter

Python parameter combination, python Parameter

The order of parameter definitions must be: ① mandatory parameter, ② default parameter, ③ optional parameter, ④ name keyword parameter, ⑤ keyword Parameter

1 # a and B are mandatory parameters; c is the default parameter; args is a variable parameter; kw is the keyword parameter 2 def f1 (a, B, c = 0, * args, ** kw): 3 print ('a = ',' B = ', B, 'c =', 'args = ', args, 'kw =', kw) 4 5 # The sequence of parameter definitions must be: mandatory parameter, default parameter, optional parameter, naming keyword parameter, keyword parameter 6 def f2 (a, B, c = 0 ,*, d, ** kw): 7 print ('a = ',' B = ', B, 'c =', 'd = ', d, 'kw = ', kw)

Call

f1(1,2)f1(1,2,3)f1(1,2,c=3)f1(1,2,3,'a','b')f1(1,2,3,'a','b',x=99,y=88,z=77,t='100')f2(1, 2, city='Shanghai', ext=None)

Call result

a= 1 b= 2 c= 0 args= () kw= {}a= 1 b= 2 c= 3 args= () kw= {}a= 1 b= 2 c= 3 args= () kw= {}a= 1 b= 2 c= 3 args= ('a', 'b') kw= {}a= 1 b= 2 c= 3 args= ('a', 'b') kw= {'x': 99, 'y': 88, 'z': 77, 't': '100'}a= 1 b= 2 c= 0 city= Shanghai kw= {'ext': None}

Input with list or dict Parameters

args=(1,2,3,4)kw={'Nation':'China','City':'Shanghai'}f1(*args,**kw)args=(1,2,3)kw={'y':33,'city':'Shanghai'}f2(*args,**kw)

Result

a= 1 b= 2 c= 3 args= (4,) kw= {'City': 'Shanghai', 'Nation': 'China'}a= 1 b= 2 c= 3 city= Shanghai kw= {'y': 33}

Therefore, for any functionfunc(*args, **kw)It is called, no matter how its parameters are defined.