python code

#enumerate 的使用
def out(seq):
    for i,item in enumerate(seq):
        print(i,item)
out(['小明','小名','小铭'])
# 字典推导式
L1 = ['username','password','name','work']
L2 = ['admin','123456','xin yue','engineer']
d = {i:j for i,j in zip(L1,L2)}
print(d)
# 集合生成式
L1 = ['username','password','name','work']
L2 = ['admin','123456','xin yue','engineer']
L2.extend(L1)
S = {i for i in L2}
print(S)

from collections import OrderedDict


def from_key_val_list(value):
    """获取一个对象并测试它是否可以表示为字典,除非它不能这样表示，否则返回OrderedDict"""
    if value is None:
        return None

    if isinstance(value,(str,bytes,int,bool)):
        raise ValueError('cannot encode objects that are not 2-tuple!')

    return OrderedDict(value)

# test
print(from_key_val_list([('key', 'val')]))  # OrderedDict([('key', 'val')])
print(from_key_val_list({'key': 'val'}))    # OrderedDict([('key', 'val')])
print(from_key_val_list('string'))  # ValueError: cannot encode objects that are not 2-tuples

from collections.abc import Mapping

def to_key_val_list(value):
    """获取一个对象并测试它是否可以表示为字典. 如果可以的话，返回一个元组列表"""
    if value is None:
        return None

    if isinstance(value,(str,bytes,int,bool)):
        raise ValueError('cannot encode objects that are not 2-tuple!')

    if isinstance(value,Mapping):
        value = value.items()

    return list(value)

# test
print(to_key_val_list([('key', 'val')]))    # [('key', 'val')]
print(to_key_val_list({'key': 'val'}))      # [('key', 'val')]
print(to_key_val_list('string'))    # ValueError: cannot encode objects that are not 2-tuples.

def guess_filename(obj):
    """ Tries to guess the filename of the given object."""
    name = getattr(obj,'name',None)
    if (name and isinstance(name,(str, bytes)) and
            name[0] != '<' and name[-1] != '>'):
        return os.path.basename(name)

def urldefragauth(url):
    """ Given a url remove the fragment and the authentication part."""

    scheme, netloc, path, params, query, fragment = urlparse(url)

    if not netloc:
        netloc, path = path, netloc

    netloc = netloc.rsplit('@', 1)[-1]

    return urlunparse((scheme, netloc, path, params, query, ''))

from urllib.parse import urlparse,unquote

def get_auth_from_url(url):
    """Given a url with authentication components, extract them into a tuple of username,password"""

    parsed = urlparse(url)
    try:
        auth = (unquote(parsed.username), unquote(parsed.password))
    except (AttributeError, TypeError):
        auth = ('','')
    return auth

# test
url='http://admin:123456@127.0.0.1:8000'
print(get_auth_from_url(url))

from urllib.parse import urlparse,urlunparse

def prepend_scheme_if_needed(url, new_scheme):
    """
    Given a URL that may or may not have a scheme, prepend the given scheme.
    Does not replace a present scheme with the one provided as an argument.
    """
    scheme, netloc, path, params, query, fragment = urlparse(url, new_scheme)

    # urlparse is a finicky beast, and sometimes decides that there isn't a
    # netloc present. Assume that it's being over-cautious, and switch netloc
    # and path if urlparse decided there was no netloc.
    if not netloc:
        netloc, path = path, netloc

    return urlunparse((scheme, netloc, path, params, query, fragment))