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Super Kai (Kazuya Ito)
Super Kai (Kazuya Ito)

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Function in Python (1)

#python #function #parameter #argument

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*Memo:

  • My post explains a function (2).
  • My post explains parameters and arguments in a function.
  • My post explains the iterable unpacking with * and a function (1).
  • My post explains the dictionary unpacking with ** within a dictionary and function.
  • My post explains *args.
  • My post explains **kwargs.
  • My post explains a lambda.
  • My post explains a variable assignment.
  • My post explains an identifier.
  • My post explains naming convention.

A function:

  • is the statement which can do a specific task, reusing and reducing code and whose type is func.
  • must have a def, identifier, (): and its body code.
  • can have zero or more parameters.
  • can have zero or more return statements.
  • can have one or more pass statements, return statements and values to do nothing, returning None.
  • can be assigned a variable, function and class to.
  • can be defined a variable, function and class in.
  • can be written in one line.
  • can be indirectly assigned to a variable and parameter but not directly.
  • and parameter name can have letters, _, the digits except for the 1st character and can be a reserved soft keyword but cannot start with a digit and cannot be a reserved keyword and should be lower_snake_case.

A function is the statement whose type is func to do a specific task, reusing and reducing code as shown below:

def func(num1, num2): return num1+num2 print(func(3, 5)) # 8  print(func(7, 2)) # 9  print(func(1, 4)) # 5
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def func(num1, num2): return num1+num2 print(func) # <function func at 0x00000197701259E0>  print(type(func)) # <class 'function'>
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*Code is more if not using a function.

num1 = 3 num2 = 5 print(num1+num2) # 8  num1 = 7 num2 = 2 print(num1+num2) # 9  num1 = 1 num2 = 4 print(num1+num2) # 5
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Zero or more parameters can be set in a function as shown below:

def func(): print("No param") func() # No param
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def func(p1, p2='p2'): print(p1, p2) func('param1') func(p1='param1') # param1 p2  func('param1', 'param2') func('param1', p2='param2') func(p1='param1', p2='param2') func(p2='param2', p1='param1') # param1 param2
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def func(p1, /, p2='p2', *, p3='p3'): print(p1, p2, p3) func('param1') # param1 p2 p3  func('param1', 'param2') func('param1', p2='param2') # param1 param2 p3  func('param1', p3='param3') # param1 p2 param3  func('param1', 'param2', p3='param3') func('param1', p2='param2', p3='param3') # param1 param2 param3
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def func(*args, **kwargs): print(args, kwargs) func() # () {}  func(0, 1) func(*[0, 1]) # (0, 1) {}  func(A=2, B=3) func(**{'A':2, 'B':3}) # () {'A': 2, 'B': 3}  func(0, 1, A=2, B=3) func(*[0, 1], **{'A':2, 'B':3}) # (0, 1) {'A': 2, 'B': 3}
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One or more return statements can be set in a function as shown below:

def func(): return "Hello" print(func()) # Hello
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def func(): return [0, 1, 2] print(func()) # [0, 1, 2]
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def func(): return "Hello" return [0, 1, 2] print(func()) # Hello
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def func(): return [0, 1, 2] return "Hello" print(func()) # [0, 1, 2]
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def func(): return print(func()) # None
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