>>> dir(factorial) ['__annotations__', '__call__', '__class__', '__closure__', '__code__', '__defaults__', '__delattr__', '__dict__', '__dir__', '__doc__', '__eq__', '__format__', '__ge__', '__get__', '__getattribute__', '__globals__', '__gt__', '__hash__', '__init__', '__kwdefaults__', '__le__', '__lt__', '__module__', '__name__', '__ne__', '__new__', '__qualname__', '__reduce__', '__reduce_ex__', '__repr__', '__setattr__', '__sizeof__', '__str__', '__subclasshook__']?

>>> class C:pass
...
>>> obj = C()
>>> def func():pass
...
>>> sorted(set(dir(func)) - set(dir(obj))) # 計算差集，然后排序
['__annotations__', '__call__', '__closure__', '__code__', '__defaults__', '__get__', '__globals__', '__kwdefaults__', '__name__', '__qualname__']

def tag(name,*content,cls=None,**attrs):
if cls is not None:
attrs['class'] = cls

if attrs:
attrs_str = ''.join(' %s="%s" ' % (attr,value) for attr,value in sorted(attrs.items()))
else:
attrs_str=''
if content:
return '\n'.join('<%s %s >%s</%s>' % (name,attrs_str,c,name) for c in content)
else:
return '<%s%s />' % (name,attrs_str)
print(tag('br'))#定位參數 name
print(tag('p','hello'))#hello 會被*conteng捕獲 存入元組content = ('hello')
print(tag('p','hello','world'))#content = ('hello','world')
print(tag('p','hello',id=33)) #attrs={'id':33} content = ('hello')
print(tag('p','hello','world',cls='sidebar'))#cls 關鍵字傳入 cls='sidebar'
print(tag(content='testing',name='img'))#第一個參數name 也能作為關鍵字傳入
#同名鍵會綁定到對應的具名參數上，剩余的則會被**attrs捕獲
print(tag(**{'name':'img','title':'sunset boulevard','src':'sunset.jpg','cls':'framed'}))
#僅限關鍵字參數是python3.0新增的特性，在上例中，cls參數只能通過關鍵字參數指定，他一定不會捕獲未命名的定位參數
#定義函數時候，如果想指定僅限關鍵字參數，要把它們放到*的參數后面
def f(a,*,b):
return a,b
ff = f(1,b=2)
print(ff)

<br />
<p >hello</p>
<p >hello</p>
<p >world</p>
<p id="33" >hello</p>
<p class="sidebar" >hello</p>
<p class="sidebar" >world</p>
<img content="testing" />
<img class="framed" src="sunset.jpg" title="sunset boulevard" />
(1, 2)

def tag(name,*content,cls=None,**attrs):
if cls is not None:
attrs['class'] = cls
if attrs:
attrs_str = ''.join(' %s="%s" ' % (attr,value) for attr,value in sorted(attrs.items()))
else:
attrs_str=''
if content:
return '\n'.join('<%s %s >%s</%s>' % (name,attrs_str,c,name) for c in content)
else:
return '<%s%s />' % (name,attrs_str)
import inspect
sig = inspect.signature(tag)
print(sig)
my_tag = {'name':'img','title':'sun long','src':'sunlong.jpg','cls':'framed'}
bound_args = sig.bind(**my_tag)
for name,value in bound_args.arguments.items():
print(name,'=',value)
print(bound_args)

(name, *content, cls=None, **attrs)
name = img
cls = framed
attrs = {'title': 'sun long', 'src': 'sunlong.jpg'}
<BoundArguments (name='img', cls='framed', attrs={'title': 'sun long', 'src': 'sunlong.jpg'})>