Python3基礎 函數 無return、return 空或None 的效果相同

 

•        Python : 3.7.3
•          OS : Ubuntu 18.04.2 LTS
•         IDE : pycharm-community-2019.1.3
•       Conda : 4.7.5
•    typesetting : Markdown

 

code

coder@ubuntu:~$ source activate py37
(py37) coder@ubuntu:~$ ipython
Python 3.7.3 (default, Mar 27 2019, 22:11:17) 
Type 'copyright', 'credits' or 'license' for more information
IPython 7.5.0 -- An enhanced Interactive Python. Type '?' for help.

In [1]: def fun_no_return(): 
   ...:     pass 
   ...:                                                                                          

In [2]: def fun_return_none(): 
   ...:     return None 
   ...:                                                                                          

In [3]: def fun_return_empty(): 
   ...:     return 
   ...:                                                                                          

In [4]: import dis                                                                               

In [5]: dis.dis(fun_no_return)                                                                   
  2           0 LOAD_CONST               0 (None)
              2 RETURN_VALUE

In [6]: dis.dis(fun_return_empty)                                                                
  2           0 LOAD_CONST               0 (None)
              2 RETURN_VALUE

In [7]: dis.dis(fun_return_none)                                                                 
  2           0 LOAD_CONST               0 (None)
              2 RETURN_VALUE

In [8]: exit                                                                                     
(py37) coder@ubuntu:~$ conda deactivate
coder@ubuntu:~$ 

 

source_code

def dis(x=None, *, file=None, depth=None):
    """Disassemble classes, methods, functions, and other compiled objects.

    With no argument, disassemble the last traceback.

    Compiled objects currently include generator objects, async generator
    objects, and coroutine objects, all of which store their code object
    in a special attribute.
    """
    if x is None:
        distb(file=file)
        return
    # Extract functions from methods.
    if hasattr(x, '__func__'):
        x = x.__func__
    # Extract compiled code objects from...
    if hasattr(x, '__code__'):  # ...a function, or
        x = x.__code__
    elif hasattr(x, 'gi_code'):  #...a generator object, or
        x = x.gi_code
    elif hasattr(x, 'ag_code'):  #...an asynchronous generator object, or
        x = x.ag_code
    elif hasattr(x, 'cr_code'):  #...a coroutine.
        x = x.cr_code
    # Perform the disassembly.
    if hasattr(x, '__dict__'):  # Class or module
        items = sorted(x.__dict__.items())
        for name, x1 in items:
            if isinstance(x1, _have_code):
                print("Disassembly of %s:" % name, file=file)
                try:
                    dis(x1, file=file, depth=depth)
                except TypeError as msg:
                    print("Sorry:", msg, file=file)
                print(file=file)
    elif hasattr(x, 'co_code'): # Code object
        _disassemble_recursive(x, file=file, depth=depth)
    elif isinstance(x, (bytes, bytearray)): # Raw bytecode
        _disassemble_bytes(x, file=file)
    elif isinstance(x, str):    # Source code
        _disassemble_str(x, file=file, depth=depth)
    else:
        raise TypeError("don't know how to disassemble %s objects" %
                        type(x).__name__)

 

reference

• https://www.v2ex.com/amp/t/337852

 

resource

• [文檔 - English] docs.python.org/3
• [文檔 - 中文] docs.python.org/zh-cn/3
• [規范] www.python.org/dev/peps/pep-0008
• [規范] zh-google-styleguide.readthedocs.io/en/latest/google-python-styleguide/python_language_rules
• [源碼] www.python.org/downloads/source
• [ PEP ] www.python.org/dev/peps
• [平台] www.cnblogs.com
• [平台] gitee.com

 

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Python具有開源、跨平台、解釋型、交互式等特性，值得學習。
Python的設計哲學：優雅，明確，簡單。提倡用一種方法，最好是只有一種方法來做一件事。
代碼的書寫要遵守規范，這樣有助於溝通和理解。
每種語言都有獨特的思想，初學者需要轉變思維、踏實踐行、堅持積累。