Google Python 风格指南 II

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Yes: foo_bar(self, width, height, color='black', design=None, x='foo',
             emphasis=None, highlight=0)

     if (width == 0 and height == 0 and
         color == 'red' and emphasis == 'strong'):    

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x = ('This will build a very long long '
     'long long long long long long string')

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Yes:  # See details at
      # http://www.example.com/us/developer/documentation/api/content/v2.0/csv_file_name_extension_full_specification.html

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No:  # See details at
     # http://www.example.com/us/developer/documentation/api/content/\
     # v2.0/csv_file_name_extension_full_specification.html     

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Yes: if foo:
         bar()
     while x:
         x = bar()
     if x and y:
         bar()
     if not x:
         bar()
     return foo
     for (x, y) in dict.items(): ...  

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No:  if (x):
         bar()
     if not(x):
         bar()
     return (foo)

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Yes:   # Aligned with opening delimiter
       foo = long_function_name(var_one, var_two,
                                var_three, var_four)

       # Aligned with opening delimiter in a dictionary
       foo = {
           long_dictionary_key: value1 +
                                value2,
           ...
       }

       # 4-space hanging indent; nothing on first line
       foo = long_function_name(
           var_one, var_two, var_three,
           var_four)

       # 4-space hanging indent in a dictionary
       foo = {
           long_dictionary_key:
               long_dictionary_value,
           ...
       }

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No:    # Stuff on first line forbidden
      foo = long_function_name(var_one, var_two,
          var_three, var_four)

      # 2-space hanging indent forbidden
      foo = long_function_name(
        var_one, var_two, var_three,
        var_four)

      # No hanging indent in a dictionary
      foo = {
          long_dictionary_key:
              long_dictionary_value,
              ...
      }

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Yes: spam(ham[1], {eggs: 2}, [])

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No:  spam( ham[ 1 ], { eggs: 2 }, [ ] )

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Yes: if x == 4:
         print x, y
     x, y = y, x

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No:  if x == 4 :
         print x , y
     x , y = y , x

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Yes: spam(1)

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no: spam (1)

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Yes: dict['key'] = list[index]

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No:  dict ['key'] = list [index]       

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Yes: x == 1

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No:  x<1

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Yes: def complex(real, imag=0.0): return magic(r=real, i=imag)

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No:  def complex(real, imag = 0.0): return magic(r = real, i = imag)

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Yes:
     foo = 1000  # comment
     long_name = 2  # comment that should not be aligned

     dictionary = {
         "foo": 1,
         "long_name": 2,
         }

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No:
     foo       = 1000  # comment
     long_name = 2     # comment that should not be aligned

     dictionary = {
         "foo"      : 1,
         "long_name": 2,
         }

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 def fetch_bigtable_rows(big_table, keys, other_silly_variable=None):
     """Fetches rows from a Bigtable.
     Retrieves rows pertaining to the given keys from the Table instance
     represented by big_table.  Silly things may happen if
     other_silly_variable is not None.
     Args:
         big_table: An open Bigtable Table instance.
         keys: A sequence of strings representing the key of each table row
             to fetch.
         other_silly_variable: Another optional variable, that has a much
             longer name than the other args, and which does nothing.
     Returns:
         A dict mapping keys to the corresponding table row data
         fetched. Each row is represented as a tuple of strings. For
         example:
         {'Serak': ('Rigel VII', 'Preparer'),
          'Zim': ('Irk', 'Invader'),
          'Lrrr': ('Omicron Persei 8', 'Emperor')}
         If a key from the keys argument is missing from the dictionary,
         then that row was not found in the table.
     Raises:
         IOError: An error occurred accessing the bigtable.Table object.
     """
     pass

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 class SampleClass(object):
     """Summary of class here.
     Longer class information....
     Longer class information....
     Attributes:
         likes_spam: A boolean indicating if we like SPAM or not.
         eggs: An integer count of the eggs we have laid.
     """
     def __init__(self, likes_spam=False):
         """Inits SampleClass with blah."""
         self.likes_spam = likes_spam
         self.eggs = 0
     def public_method(self):
         """Performs operation blah."""

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 # We use a weighted dictionary search to find out where i is in
 # the array.  We extrapolate position based on the largest num
 # in the array and the array size and then do binary search to
 # get the exact number.
 if i & (i-1) == 0:        # true iff i is a power of 2

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 # BAD COMMENT: Now go through the b array and make sure whenever i occurs
 # the next element is i+1

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Yes: class SampleClass(object):
         pass


     class OuterClass(object):

         class InnerClass(object):
             pass


     class ChildClass(ParentClass):
         """Explicitly inherits from another class already."""

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No: class SampleClass:
        pass


    class OuterClass:

        class InnerClass:
            pass

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Yes: x = a + b
     x = '%s, %s!' % (imperative, expletive)
     x = '{}, {}!'.format(imperative, expletive)
     x = 'name: %s; score: %d' % (name, n)
     x = 'name: {}; score: {}'.format(name, n)

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No: x = '%s%s' % (a, b)  # use + in this case
    x = '{}{}'.format(a, b)  # use + in this case
    x = imperative + ', ' + expletive + '!'
    x = 'name: ' + name + '; score: ' + str(n)

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Yes: items = ['<table>']
     for last_name, first_name in employee_list:
         items.append('<tr><td>%s, %s</td></tr>' % (last_name, first_name))
     items.append('</table>')
     employee_table = ''.join(items)

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No: employee_table = '<table>'
    for last_name, first_name in employee_list:
        employee_table += '<tr><td>%s, %s</td></tr>' % (last_name, first_name)
    employee_table += '</table>'

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Yes:
     Python('Why are you hiding your eyes?')
     Gollum("I'm scared of lint errors.")
     Narrator('"Good!" thought a happy Python reviewer.')

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No:
     Python("Why are you hiding your eyes?")
     Gollum('The lint. It burns. It burns us.')
     Gollum("Always the great lint. Watching. Watching.")

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Yes:
    print ("This is much nicer.\n"
           "Do it this way.\n")

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No:
      print """This is pretty ugly.
  Don't do this.
  """

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with open("hello.txt") as hello_file:
    for line in hello_file:
        print line

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import contextlib

with contextlib.closing(urllib.urlopen("http://www.python.org/")) as front_page:
    for line in front_page:
        print line

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# TODO([email protected]): Use a "*" here for string repetition.
# TODO(Zeke) Change this to use relations.

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Yes: import os
     import sys

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No:  import os, sys

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import foo
from foo import bar
from foo.bar import baz
from foo.bar import Quux
from Foob import ar

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Yes:

  if foo: bar(foo)

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No:

  if foo: bar(foo)
  else:   baz(foo)

  try:               bar(foo)
  except ValueError: baz(foo)

  try:
      bar(foo)
  except ValueError: baz(foo)

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def main():
      ...

if __name__ == '__main__':
    main()