1. 动态导入代码
动态导入模块：使用importlib.import_module，参考Django的动态引入模块
def import_string(dotted_path): """ Import a dotted module path and return the attribute/class designated by the last name in the path. Raise ImportError if the import failed. """ try: module_path, class_name = dotted_path.rsplit('.', 1) except ValueError as err: raise ImportError("%s doesn't look like a module path" % dotted_path) from err module = import_module(module_path) try: return getattr(module, class_name) #判断module模块中是否存在class_name属性或者类 except AttributeError as err: raise ImportError('Module "%s" does not define a "%s" attribute/class' % ( module_path, class_name) ) from err
2. 强制关键参数
用法：当我们希望函数的某些参数强制使用关键字参数时，可以将强制关键字参数放到某个*后面就能得到这种效果
>>> def f(a, b, *, c='x', d='y', e='z'): ... return 'Hello' # To pass the value for c, d, and e you # will need to explicitly pass it as # "key=value" named arguments: >>> f(1, 2, 'p', 'q', 'v') TypeError: "f() takes 2 positional arguments but 5 were given" >>> f(1, 2, c='p', d='q',e='v') 'Hello'
3. 注册退出函数
atexit.register()装饰器：会在Python解释器中注册一个退出函数，也就是说，他会在脚本退出之前请求调用这个特殊函数
4. print函数的end和sep参数
print函数的定义 def print(self, *args, sep=' ', end='\n', file=None): # known special case of print """ print(value, ..., sep=' ', end='\n', file=sys.stdout, flush=False) Prints the values to a stream, or to sys.stdout by default. Optional keyword arguments: file: a file-like object (stream); defaults to the current sys.stdout. sep: string inserted between values, default a space. end: string appended after the last value, default a newline. flush: whether to forcibly flush the stream. """ pass参数含义： sep：分割值与值，默认是一个空格end：附件到最后一个值，默认是一个新行file：指定打印的输出位置，默认是sys.stdout
