Python于Web 2.0网站的应用 - QCon Beijing 2010

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在QCon Beijing 2010上的演讲

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  • Hi All, We are planning to start new devops online batch on this week... If any one interested to attend the demo please register in our website... For this batch we are also provide everyday recorded sessions with Materials. For more information feel free to contact us : siva@keylabstraining.com. For Course Content and Recorded Demo Click Here : http://www.keylabstraining.com/devops-online-training-tutorial
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  • Learning Python, 5th Edition --- http://amzn.to/1XEkpGP
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  • Automate the Boring Stuff with Python: Practical Programming for Total Beginners --- http://amzn.to/1LytEaR
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  • Python Crash Course: A Hands-On, Project-Based Introduction to Programming --- http://amzn.to/1RXjA7O
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Python于Web 2.0网站的应用 - QCon Beijing 2010

  1. 1. Python Web 2.0 QCon Beijing 2010 http://www.flickr.com/photos/arnolouise/2986467632/
  2. 2. About Me • Python • 2002 Python • 2004 Python • http://www.douban.com/ people/hongqn/ • hongqn@douban.com • http://twitter.com/hongqn
  3. 3. Python • Python is a programming language that lets you work more quickly and integrate your systems more effectively. You can learn to use Python and see almost immediate gains in productivity and lower maintenance costs. (via http://python.org/)
  4. 4. Languages in C 27% Javascript 12% C++ Python 3% 58% (Pyrex/R/Erlang/Go/Shell) 1%
  5. 5. Why Python?
  6. 6. • Hello World: 1
  7. 7. • Hello World: 1 • :1
  8. 8. • Hello World: 1 • :1 • :1
  9. 9. • Hello World: 1 • :1 • :1 • :3
  10. 10. : 13
  11. 11. : 13 import os from collections import defaultdict d = defaultdict(int) for dirpath, dirnames, filenames in os.walk('.'): for filename in filenames: path = os.path.join(dirpath, filename) ext = os.path.splitext(filename)[1] d[ext] += len(list(open(path))) for ext, n_lines in d.items(): print ext, n_lines
  12. 12. • • Pythonic
  13. 13. • 1. svn ci 2. svn up 3. restart
  14. 14. • Web • • •
  15. 15. • Battery Included: 200+ • PyPI: 9613 packages currently • / / / / / / /... • easily extensible
  16. 16. Python
  17. 17. Python
  18. 18. Python Just kidding :-p
  19. 19. Web Server
  20. 20. Web Server • python -m SimpleHTTPServer
  21. 21. Web Server • python -m SimpleHTTPServer
  22. 22. web.py http://webpy.org/ import web urls = ( '/(.*)', 'hello' ) app = web.application(urls, globals()) class hello: def GET(self, name): if not name: name = 'World' return 'Hello, ' + name + '!' if __name__ == "__main__": app.run()
  23. 23. Flask http://flask.pocoo.org/ import flask import Flask app = Flask(__name__) @app.route("/<name>") def hello(name): if not name: name = 'World' return 'Hello, ' + name + '!' if __name__ == "__main__": app.run()
  24. 24. WSGI http://www.python.org/dev/peps/pep-0333/
  25. 25. Why so many Python web frameworks? • Because you can write your own framework in 3 hours and a total of 60 lines of Python code. • http://bitworking.org/news/ Why_so_many_Python_web_frameworks
  26. 26. doctest def cube(x): """ >>> cube(10) 1000 """ return x * x def _test(): import doctest doctest.testmod() if __name__ == "__main__": _test()
  27. 27. nose http://somethingaboutorange.com/mrl/projects/nose/ from cube import cube def test_cube(): result = cube(10) assert result == 1000
  28. 28. numpy http://numpy.scipy.org/ >>> from numpy import * >>> A = arange(4).reshape(2, 2) >>> A array([[0, 1], [2, 3]]) >>> dot(A, A.T) array([[ 1, 3], [ 3, 13]])
  29. 29. ipython http://numpy.scipy.org/ $ ipython -pylab In [1]: X = frange(0, 10, 0.1) In [2]: Y = [sin(x) for x in X] In [3]: plot(X, Y)
  30. 30. ipython http://numpy.scipy.org/ $ ipython -pylab In [1]: X = frange(0, 10, 0.1) In [2]: Y = [sin(x) for x in X] In [3]: plot(X, Y)
  31. 31. virtualenv http://virtualenv.openplans.org/ python $ python go-pylons.py --no-site-packages mydevenv $ cd mydevenv $ source bin/activate (mydevenv)$ paster create -t new9 helloworld
  32. 32. Pyrex/Cython cdef extern from "math.h" double sin(double) cdef double f(double x): return sin(x*x)
  33. 33. Pythonic
  34. 34. >>> import this The Zen of Python, by Tim Peters http://bit.ly/pyzencn Beautiful is better than ugly. Explicit is better than implicit. Simple is better than complex. Complex is better than complicated. Flat is better than nested. Sparse is better than dense. Readability counts. Special cases aren't special enough to break the rules.   Although practicality beats purity. Errors should never pass silently. Unless explicitly silenced.  
  35. 35. In the face of ambiguity, refuse the temptation to guess. There should be one-- and preferably only one --obvious way to do it. Although that way may not be Python obvious at first unless you're Dutch.   Now is better than never. Although never is often better than *right* now.   If the implementation is hard to explain, it's a bad idea. If the implementation is easy to   explain, it may be a good idea. Namespaces are one honking great idea -- let's do more of those!
  36. 36. Simple is better than complex class HelloWorld { public static void main(String args[]) { System.out.println("Hello World!"); } }
  37. 37. Simple is better than complex print "Hello World!"
  38. 38. Readability counts
  39. 39. Readability counts • {} end
  40. 40. Readability counts • {} end • (except "@" for decorators)
  41. 41. Readability counts • {} end • (except "@" for decorators) if limit is not None and len(ids)>limit: ids = random.sample(ids, limit)
  42. 42. TOOWTDI • There (should be) Only One Way To Do It. • vs. Perlish TIMTOWTDI (There Is More Than One Way To Do It)
  43. 43. TOOWTDI • There (should be) Only One Way To Do It. • vs. Perlish TIMTOWTDI (There Is More Than One Way To Do It) a = [1, 2, 3, 4, 5] b = [] for i in range(len(a)): b.append(a[i]*2)
  44. 44. TOOWTDI • There (should be) Only One Way To Do It. • vs. Perlish TIMTOWTDI (There Is More Than One Way To Do It) a = [1, 2, 3, 4, 5] b = [] for i in range(len(a)): b.append(a[i]*2)
  45. 45. TOOWTDI • There (should be) Only One Way To Do It. • vs. Perlish TIMTOWTDI (There Is More Than One Way To Do It) a = [1, 2, 3, 4, 5] b = [] b = [] for x in a: for i in range(len(a)): b.append(x*2) b.append(a[i]*2)
  46. 46. TOOWTDI • There (should be) Only One Way To Do It. • vs. Perlish TIMTOWTDI (There Is More Than One Way To Do It) a = [1, 2, 3, 4, 5] b = [] b = [] for x in a: for i in range(len(a)): b.append(x*2) b.append(a[i]*2)
  47. 47. TOOWTDI • There (should be) Only One Way To Do It. • vs. Perlish TIMTOWTDI (There Is More Than One Way To Do It) b = [x*2 for x in a]
  48. 48. http://twitter.com/robbinfan/status/9879724095 http://twitter.com/hongqn/status/9883515681
  49. 49. Python C http://www.flickr.com/photos/nicksieger/281055485/ http://www.flickr.com/photos/nicksieger/281055530/
  50. 50. Ruby http://www.flickr.com/photos/nicksieger/280661836/
  51. 51. Java http://www.flickr.com/photos/nicksieger/280662707/
  52. 52. Python
  53. 53. • svn
  54. 54. • svn • ( list)
  55. 55. • svn • ( list) • +
  56. 56. • svn • ( list) • + • parser
  57. 57. config.py MEMCACHED_ADDR = ['localhost:11211'] from local_config import *
  58. 58. config.py MEMCACHED_ADDR = ['localhost:11211'] from local_config import * local_config.py MEMCACHED_ADDR = [ 'frodo:11211', 'sam:11211', 'pippin:11211', 'merry:11211', ]
  59. 59. config.py MEMCACHED_ADDR = ['localhost:11211'] from local_config import * .py local_config.py exec MEMCACHED_ADDR = [ 'frodo:11211', 'sam:11211', 'pippin:11211', 'merry:11211', ]
  60. 60.
  61. 61. class GroupUI(object): def new_topic(self, request): if self.group.can_post(request.user): return new_topic_ui(self.group) else: request.response.set_status(403, "Forbidden") return error_403_ui(msg=" ") def join(self, request): if self.group.can_join(request.user): ... class Group(object): def can_post(self, user): return self.group.has_member(user) def can_join(self, user): return not self.group.has_banned(user)
  62. 62. class GroupUI(object): @check_permission('post', msg=" ") def new_topic(self, request): return new_topic_ui(self.group) @check_permission('join', msg=" ") def join(self, request): ... class Group(object): def can_post(self, user): return self.group.has_member(user) def can_join(self, user): return not self.group.has_banned(user)
  63. 63. decorator def print_before_exec(func): def _(*args, **kwargs): print "decorated" return func(*args, **kwargs) return _ @print_before_exec def double(x): print x*2 double(10)
  64. 64. decorator def print_before_exec(func): def _(*args, **kwargs): print "decorated" return func(*args, **kwargs) return _ decorated @print_before_exec def double(x): 20 print x*2 double(10)
  65. 65. class check_permission(object): def __init__(self, action, msg=None): self.action = action self.msg = msg def __call__(self, func): def _(ui, req, *args, **kwargs): f = getattr(ui.perm_obj, 'can_' + self.action) if f(req.user): return func(ui, *args, **kwargs) raise BadPermission(ui.perm_obj, self.action, self.msg) return _
  66. 66. class check_permission(object): def __init__(self, action, msg=None): self.action = action self.msg = msg def __call__(self, func): def _(ui, req, *args, **kwargs): f = getattr(ui.perm_obj, 'can_' + self.action) if f(req.user): return func(ui, *args, **kwargs) raise BadPermission(ui.perm_obj, self.action, self.msg) return _
  67. 67. class check_permission(object): def __init__(self, action, msg=None): self.action = action self.msg = msg def __call__(self, func): def _(ui, req, *args, **kwargs): f = getattr(ui.perm_obj, 'can_' + self.action) if f(req.user): return func(ui, *args, **kwargs) raise BadPermission(ui.perm_obj, self.action, self.msg) return _
  68. 68. class check_permission(object): def __init__(self, action, msg=None): self.action = action self.msg = msg def __call__(self, func): def _(ui, req, *args, **kwargs): f = getattr(ui.perm_obj, 'can_' + self.action) if f(req.user): return func(ui, *args, **kwargs) raise BadPermission(ui.perm_obj, self.action, self.msg) return _
  69. 69. class check_permission(object): def __init__(self, action, msg=None): self.action = action self.msg = msg def __call__(self, func): def _(ui, req, *args, **kwargs): f = getattr(ui.perm_obj, 'can_' + self.action) if f(req.user): return func(ui, *args, **kwargs) raise BadPermission(ui.perm_obj, self.action, self.msg) return _
  70. 70. class check_permission(object): def __init__(self, action, msg=None): self.action = action self.msg = msg def __call__(self, func): def _(ui, req, *args, **kwargs): f = getattr(ui.perm_obj, 'can_' + self.action) if f(req.user): return func(ui, *args, **kwargs) raise BadPermission(ui.perm_obj, self.action, self.msg) return _
  71. 71. class GroupUI(object): @check_permission('post', msg=" ") def new_topic(self, request): return new_topic_ui(self.group) @check_permission('join', msg=" ") def join(self, request): ... class Group(object): def can_post(self, user): return self.group.has_member(user) def can_join(self, user): return not self.group.has_banned(user)
  72. 72.
  73. 73. def send_notification_mail(email, subject, body): msg = MSG_SEND_MAIL + '0' + email + '0' + subject + '0' + body mq.put(msg) def async_worker(): msg = mq.get() msg = msg.split('0') cmd = msg[0] if cmd == MSG_SEND_MAIL: email, subject, body = msg[1:] fromaddr = 'no-reply@douban.com' email_body = make_email_body(fromaddr, email, subject, body) smtp = smtplib.SMTP('mail') smtp.sendmail(fromaddr, email, email_body) elif cmd == MSG_xxxx: ... elif cmd == MSG_yyyy: ...
  74. 74. @async def send_notification_mail(email, subject, body): fromaddr = 'no-reply@douban.com' email_body = make_email_body(fromaddr, email, subject, body) smtp = smtplib.SMTP('mail') smtp.sendmail(fromaddr, email, email_body)
  75. 75. def async(func): mod = sys.modules[func.__module__] fname = 'origin_' + func.__name__ mod.__dict__[fname] = func def _(*a, **kw): body = cPickle.dumps((mod.__name__, fname, a, kw)) mq.put(body) return _ def async_worker(): modname, fname, a, kw = cPickle.loads(mq.get()) __import__(modname) mod = sys.modules[modname] mod.__dict__[fname](*a, **kw)
  76. 76. def async(func): mod = sys.modules[func.__module__] fname = 'origin_' + func.__name__ mod.__dict__[fname] = func def _(*a, **kw): body = cPickle.dumps((mod.__name__, fname, a, kw)) mq.put(body) return _ def async_worker(): modname, fname, a, kw = cPickle.loads(mq.get()) __import__(modname) mod = sys.modules[modname] mod.__dict__[fname](*a, **kw)
  77. 77. def async(func): mod = sys.modules[func.__module__] fname = 'origin_' + func.__name__ mod.__dict__[fname] = func def _(*a, **kw): body = cPickle.dumps((mod.__name__, fname, a, kw)) mq.put(body) return _ def async_worker(): modname, fname, a, kw = cPickle.loads(mq.get()) __import__(modname) mod = sys.modules[modname] mod.__dict__[fname](*a, **kw)
  78. 78. def async(func): mod = sys.modules[func.__module__] fname = 'origin_' + func.__name__ mod.__dict__[fname] = func def _(*a, **kw): body = cPickle.dumps((mod.__name__, fname, a, kw)) mq.put(body) return _ def async_worker(): modname, fname, a, kw = cPickle.loads(mq.get()) __import__(modname) mod = sys.modules[modname] mod.__dict__[fname](*a, **kw)
  79. 79. def async(func): mod = sys.modules[func.__module__] fname = 'origin_' + func.__name__ mod.__dict__[fname] = func def _(*a, **kw): body = cPickle.dumps((mod.__name__, fname, a, kw)) mq.put(body) return _ def async_worker(): modname, fname, a, kw = cPickle.loads(mq.get()) __import__(modname) mod = sys.modules[modname] mod.__dict__[fname](*a, **kw)
  80. 80. def async(func): mod = sys.modules[func.__module__] fname = 'origin_' + func.__name__ mod.__dict__[fname] = func def _(*a, **kw): body = cPickle.dumps((mod.__name__, fname, a, kw)) mq.put(body) return _ def async_worker(): modname, fname, a, kw = cPickle.loads(mq.get()) __import__(modname) mod = sys.modules[modname] mod.__dict__[fname](*a, **kw)
  81. 81. def async(func): mod = sys.modules[func.__module__] fname = 'origin_' + func.__name__ mod.__dict__[fname] = func def _(*a, **kw): body = cPickle.dumps((mod.__name__, fname, a, kw)) mq.put(body) return _ def async_worker(): modname, fname, a, kw = cPickle.loads(mq.get()) __import__(modname) mod = sys.modules[modname] mod.__dict__[fname](*a, **kw)
  82. 82. def async(func): mod = sys.modules[func.__module__] fname = 'origin_' + func.__name__ mod.__dict__[fname] = func def _(*a, **kw): body = cPickle.dumps((mod.__name__, fname, a, kw)) mq.put(body) return _ def async_worker(): modname, fname, a, kw = cPickle.loads(mq.get()) __import__(modname) mod = sys.modules[modname] mod.__dict__[fname](*a, **kw)
  83. 83. • cache (SQL, , etc)
  84. 84. def get_latest_review_id(): review_id = mc.get('latest_review_id') if review_id is None: review_id = exc_sql("select max(id) from review") mc.set('latest_review_id', review_id) return review_id
  85. 85. @cache('latest_review_id') def get_latest_review_id(): return exc_sql("select max(id) from review")
  86. 86. def cache(key): def deco(func): def _(*args, **kwargs): r = mc.get(key) if r is None: r = func(*args, **kwargs) mc.set(key, r) return r return _ return deco
  87. 87. def cache(key): def deco(func): def _(*args, **kwargs): r = mc.get(key) if r is None: r = func(*args, **kwargs) mc.set(key, r) return r return _ return deco
  88. 88. cache key def get_review(id): key = 'review:%s' % id review = mc.get(key) if review is None: # cache miss id, author_id, text = exc_sql("select id, author_id, text from review where id=%s", id) review = Review(id, author_id, text) mc.set(key, review) return review
  89. 89. cache key decorator @cache('review:{id}') def get_review(id): id, author_id, text = exc_sql("select id, author_id, text from review where id=%s", id) return Review(id, author_id, text)
  90. 90. def cache(key_pattern, expire=0): def deco(f): arg_names, varargs, varkw, defaults = inspect.getargspec(f) if varargs or varkw: raise Exception("not support varargs") gen_key = gen_key_factory(key_pattern, arg_names, defaults) def _(*a, **kw): key = gen_key(*a, **kw) r = mc.get(key) if r is None: r = f(*a, **kw) mc.set(key, r, expire) return r return _ return deco
  91. 91. def cache(key_pattern, expire=0): def deco(f): arg_names, varargs, varkw, defaults = inspect.getargspec(f) if varargs or varkw: raise Exception("not support varargs") gen_key = gen_key_factory(key_pattern, arg_names, defaults) def _(*a, **kw): key = gen_key(*a, **kw) r = mc.get(key) if r is None: r = f(*a, **kw) mc.set(key, r, expire) return r return _ return deco
  92. 92. def cache(key_pattern, expire=0): def deco(f): arg_names, varargs, varkw, defaults = inspect.getargspec(f) if varargs or varkw: raise Exception("not support varargs") gen_key = gen_key_factory(key_pattern, arg_names, defaults) def _(*a, **kw): key = gen_key(*a, **kw) r = mc.get(key) if r is None: r = f(*a, **kw) mc.set(key, r, expire) return r return _ return deco
  93. 93. inspect.getargspec >>> import inspect >>> def f(a, b=1, c=2): ... pass ... >>> inspect.getargspec(f) ArgSpec(args=['a', 'b', 'c'], varargs=None, keywords=None, defaults=(1, 2)) >>> >>> >>> def f(a, b=1, c=2, *args, **kwargs): ... pass ... >>> inspect.getargspec(f) ArgSpec(args=['a', 'b', 'c'], varargs='args', keywords='kwargs', defaults=(1, 2))
  94. 94. def cache(key_pattern, expire=0): def deco(f): arg_names, varargs, varkw, defaults = inspect.getargspec(f) if varargs or varkw: raise Exception("not support varargs") gen_key = gen_key_factory(key_pattern, arg_names, defaults) def _(*a, **kw): key = gen_key(*a, **kw) r = mc.get(key) if r is None: r = f(*a, **kw) mc.set(key, r, expire) return r return _ return deco
  95. 95. def cache(key_pattern, expire=0): def deco(f): arg_names, varargs, varkw, defaults = inspect.getargspec(f) if varargs or varkw: raise Exception("not support varargs") gen_key = gen_key_factory(key_pattern, arg_names, defaults) def _(*a, **kw): key = gen_key(*a, **kw) r = mc.get(key) if r is None: hint: r = f(*a, **kw) mc.set(key, r, expire) return r • str.format in python 2.6: '{id}'.format(id=1) => '1' return _ return deco • dict(zip(['a', 'b', 'c'], [1, 2, 3])) => {'a': 1, 'b': 2, 'c': 3}
  96. 96. def cache(key_pattern, expire=0): def deco(f): arg_names, varargs, varkw, defaults = inspect.getargspec(f) if varargs or varkw: raise Exception("not support varargs") gen_key = gen_key_factory(key_pattern, arg_names, defaults) def _(*a, **kw): key = gen_key(*a, **kw) r = mc.get(key) if r is None: hint: r = f(*a, **kw) mc.set(key, r, expire) return r • str.format in python 2.6: '{id}'.format(id=1) => '1' return _ return deco • dict(zip(['a', 'b', 'c'], [1, 2, 3])) => {'a': 1, 'b': 2, 'c': 3}
  97. 97. def cache(key_pattern, expire=0): def deco(f): arg_names, varargs, varkw, defaults = inspect.getargspec(f) if varargs or varkw: raise Exception("not support varargs") gen_key = gen_key_factory(key_pattern, arg_names, defaults) def _(*a, **kw): key = gen_key(*a, **kw) r = mc.get(key) if r is None: r = f(*a, **kw) mc.set(key, r, expire) return r return _ return deco
  98. 98. • feed feed entry_id
  99. 99. class Feed(object): def get_entries(self, limit=10): ids = exc_sqls("select id from entry where feed_id= %s order by id desc limit %s", (self.id, limit)) return [Entry.get(id) for id in ids] class FeedCollection(object): def get_entries(self, limit=10): mixed_entries = [] for feed in self.feeds: entries = feed.get_entries(limit=limit) mixed_entries += entries mixed_entries.sort(key=lambda e: e.id, reverse=True) return mixed_entries[:10]
  100. 100. class Feed(object): def get_entries(self, limit=10): ids = exc_sqls("select id from entry where feed_id= %s order by id desc limit %s", (self.id, limit)) return [Entry.get(id) for id in ids] class FeedCollection(object): def get_entries(self, limit=10): mixed_entries = [] for feed in self.feeds: entries = feed.get_entries(limit=limit) mixed_entries += entries mixed_entries.sort(key=lambda e: e.id, reverse=True) return mixed_entries[:10]
  101. 101. class Feed(object): def get_entries(self, limit=10): ids = exc_sqls("select id from entry where feed_id= %s order by id desc limit %s", (self.id, limit)) return [Entry.get(id) for id in ids] class FeedCollection(object): def get_entries(self, limit=10): mixed_entries = [] for feed in self.feeds: entries = feed.get_entries(limit=limit) mixed_entries += entries mixed_entries.sort(key=lambda e: e.id, reverse=True) return mixed_entries[:10]
  102. 102. class Feed(object): def get_entries(self, limit=10): ids = exc_sqls("select id from entry where feed_id= %s order by id desc limit %s", (self.id, limit)) return [Entry.get(id) for id in ids] class FeedCollection(object): = def get_entries(self, limit=10): len(self.feeds) * limit mixed_entries = [] for feed in self.feeds: entries = feed.get_entries(limit=limit) mixed_entries += entries mixed_entries.sort(key=lambda e: e.id, reverse=True) return mixed_entries[:10]
  103. 103. class Feed(object): def get_entries(self, limit=10): ids = exc_sqls("select id from entry where feed_id= %s order by id desc limit %s", (self.id, limit)) return [Entry.get(id) for id in ids] class FeedCollection(object): Entry.get = def get_entries(self, limit=10): len(self.feeds-1) * limit mixed_entries = [] for feed in self.feeds: entries = feed.get_entries(limit=limit) mixed_entries += entries mixed_entries.sort(key=lambda e: e.id, reverse=True) return mixed_entries[:10]
  104. 104. iterator and generator def fib(): x, y = 1, 1 while True: yield x x, y = y, x+y def odd(seq): return (n for n in seq if n%2) def less_than(seq, upper_limit): for number in seq: if number >= upper_limit: break yield number print sum(odd(less_than(fib(), 4000000)))
  105. 105. itertools • count([n]) --> n, n+1, n+2 • cycle(p) --> p0, p1, ... plast, p0, p1, ... • repeat(elem [,n]) --> elem, elem, elem, ... endless or up to n times • izip(p, q, ...) --> (p[0], q[0]), (p[1], q[1]), ... • islice(seq, [start,] stop [, step]) --> elements from seq[start:stop:step] • ... and more ...
  106. 106. class Feed(object): def iter_entries(self): start_id = sys.maxint while True: entry_ids = exc_sqls("select id from entry where feed_id=%s and id<%s order by id desc limit 5", (self.id, start_id)) if not entry_ids: break for entry_id in entry_ids: yield Entry.get(entry_id) start_id = entry_ids[-1] class FeedCollection(object): def iter_entries(self): return imerge(*[feed.iter_entries() for feed in self.feeds]) def get_entries(self, limit=10): return list(islice(self.iter_entries(), limit))
  107. 107. class Feed(object): def iter_entries(self): start_id = sys.maxint while True: entry_ids = exc_sqls("select id from entry where feed_id=%s and id<%s order by id desc limit 5", (self.id, start_id)) if not entry_ids: break for entry_id in entry_ids: yield Entry.get(entry_id) start_id = entry_ids[-1] class FeedCollection(object): def iter_entries(self): return imerge(*[feed.iter_entries() for feed in self.feeds]) def get_entries(self, limit=10): return list(islice(self.iter_entries(), limit))
  108. 108. class Feed(object): def iter_entries(self): start_id = sys.maxint while True: entry_ids = exc_sqls("select id from entry where feed_id=%s and id<%s order by id desc limit 5", (self.id, start_id)) if not entry_ids: break for entry_id in entry_ids: yield Entry.get(entry_id) start_id = entry_ids[-1] class FeedCollection(object): def iter_entries(self): return imerge(*[feed.iter_entries() for feed in self.feeds]) def get_entries(self, limit=10): return list(islice(self.iter_entries(), limit))
  109. 109. class Feed(object): def iter_entries(self): start_id = sys.maxint while True: entry_ids = exc_sqls("select id from entry where feed_id=%s and id<%s order by id desc limit 5", (self.id, start_id)) if not entry_ids: break for entry_id in entry_ids: yield Entry.get(entry_id) start_id = entry_ids[-1] class FeedCollection(object): def iter_entries(self): return imerge(*[feed.iter_entries() for feed in self.feeds]) def get_entries(self, limit=10): return list(islice(self.iter_entries(), limit))
  110. 110. class Feed(object): def iter_entries(self): start_id = sys.maxint while True: entry_ids = exc_sqls("select id from entry where feed_id=%s and id<%s order by id desc limit 5", (self.id, start_id)) if not entry_ids: break for entry_id in entry_ids: yield Entry.get(entry_id) start_id = entry_ids[-1] class FeedCollection(object): def iter_entries(self): return imerge(*[feed.iter_entries() for feed in self.feeds]) def get_entries(self, limit=10): return list(islice(self.iter_entries(), limit))
  111. 111. class Feed(object): def iter_entries(self): start_id = sys.maxint while True: entry_ids = exc_sqls("select id from entry where feed_id=%s and id<%s order by id desc limit 5", (self.id, start_id)) if not entry_ids: break for entry_id in entry_ids: = yield Entry.get(entry_id) len(self.feeds) * 5 ~ start_id = entry_ids[-1] len(self.feeds)*5 + limit -5 class FeedCollection(object): def iter_entries(self): return imerge(*[feed.iter_entries() for feed in self.feeds]) def get_entries(self, limit=10): return list(islice(self.iter_entries(), limit))
  112. 112. class Feed(object): def iter_entries(self): start_id = sys.maxint while True: entry_ids = exc_sqls("select id from entry where feed_id=%s and id<%s order by id desc limit 5", (self.id, start_id)) if not entry_ids: break for entry_id in entry_ids: yield Entry.get(entry_id) start_id = entry_ids[-1] Entry.get = 0 ~ len(self.feeds)-1 class FeedCollection(object): def iter_entries(self): return imerge(*[feed.iter_entries() for feed in self.feeds]) def get_entries(self, limit=10): return list(islice(self.iter_entries(), limit))
  113. 113. decorator generator
  114. 114.
  115. 115. class User(object): def __init__(self, id, username, screen_name, sig): self.id = id self.username = username self.screen_name = screen_name self.sig = sig user = User('1002211', 'hongqn', 'hongqn', " ")
  116. 116. cPickle vs. marshal $ python -m timeit -s ' > from user import user > from cPickle import dumps, loads > s = dumps(user, 2)' > 'loads(s)' 100000 loops, best of 3: 6.6 usec per loop $ python -m timeit -s ' > from user import user > from marshal import dumps, loads > d = (user.id, user.username, user.screen_name, user.sig) > s = dumps(d, 2)' 'loads(s)' 1000000 loops, best of 3: 0.9 usec per loop
  117. 117. cPickle vs. marshal $ python -m timeit -s ' > from user import user > from cPickle import dumps, loads > s = dumps(user, 2)' > 'loads(s)' 7 100000 loops, best of 3: 6.6 usec per loop $ python -m timeit -s ' > from user import user > from marshal import dumps, loads > d = (user.id, user.username, user.screen_name, user.sig) > s = dumps(d, 2)' 'loads(s)' 1000000 loops, best of 3: 0.9 usec per loop
  118. 118. cPickle vs. marshal $ python -m timeit -s ' > from user import user > from cPickle import dumps, loads > s = dumps(user, 2)' > 'loads(s)' 7 100000 loops, best of 3: 6.6 usec per loop $ python -m timeit -s ' > from user import user > from marshal import dumps, loads > d = (user.id, user.username, user.screen_name, user.sig) > s = dumps(d, 2)' 'loads(s)' 1000000 loops, best of 3: 0.9 usec per loop
  119. 119. cPickle vs. marshal $ python -c timeit ' > import cPickle, marshal > from user import user > print "pickle:", len(cPickle.dumps(user, 2)) > print "marshal:", len(marshal.dumps((user.id, > user.username, user.screen_name, user.sig), 2))' pickle: 129 marshal: 74 43%
  120. 120. cPickle vs. marshal $ python -c timeit ' > import cPickle, marshal > from user import user > print "pickle:", len(cPickle.dumps(user, 2)) > print "marshal:", len(marshal.dumps((user.id, > user.username, user.screen_name, user.sig), 2))' pickle: 129 marshal: 74 43%
  121. 121. namedtuple from collections import namedtuple User = namedtuple('User', 'id username screen_name sig') user = User('1002211', 'hongqn', 'hongqn', sig=" ") user.username -> 'hongqn'
  122. 122. __metaclass__ class User(tuple): __metaclass__ = NamedTupleMetaClass __attrs__ = ['id', 'username', 'screen_name', 'sig'] user = User('1002211', 'hongqn', 'hongqn', sig=" ") s = marshal.dumps(user.__marshal__()) User.__load_marshal__(marshal.loads(s))
  123. 123. from operator import itemgetter class NamedTupleMetaClass(type): def __new__(mcs, name, bases, dict): assert bases == (tuple,) for i, a in enumerate(dict['__attrs__']): dict[a] = property(itemgetter(i)) dict['__slots__'] = () dict['__marshal__'] = tuple dict['__load_marshal__'] = classmethod(tuple.__new__) dict['__getnewargs__'] = lambda self: tuple(self) argtxt = repr(tuple(attrs)).replace("'", "")[1:-1] template = """def newfunc(cls, %(argtxt)s): return tuple.__new__(cls, (%(argtxt)s))""" % locals() namespace = {} exec template in namespace dict['__new__'] = namespace['newfunc'] return type.__new__(mcs, name, bases, dict)
  124. 124. Warning!
  125. 125. • request.get_environ(key) • e.g. request.get_environ('REMOTE_ADDR') --> request.remote_addr
  126. 126. descriptor • __get__, __set__ __delete__ class Descriptor(object): def __get__(self, instance, owner): return 'descriptor' class Owner(object): attr = Descriptor() owner = Owner() owner.attr --> 'descriptor'
  127. 127. descriptor • classmethod • staticmethod • property class C(object): def get_x(self): return self._x def set_x(self, x): self._x = x x = property(get_x, set_x)
  128. 128. class environ_getter(object): def __init__(self, key, default=None): self.key = key self.default = default def __get__(self, obj, objtype): if obj is None: return self return obj.get_environ(self.key, self.default) class HTTPRequest(quixote.http_request.HTTPRequest): for key in ['HTTP_REFERER', 'REMOTE_ADDR', 'SERVER_NAME', 'REQUEST_URI', 'HTTP_HOST']: locals()[key.lower()] = environ_getter(key) locals() del key
  129. 129. class environ_getter(object): def __init__(self, key, default=None): self.key = key self.default = default def __get__(self, obj, objtype): if obj is None: return self return obj.get_environ(self.key, self.default) class HTTPRequest(quixote.http_request.HTTPRequest): for key in ['HTTP_REFERER', 'REMOTE_ADDR', 'SERVER_NAME', 'REQUEST_URI', 'HTTP_HOST']: locals()[key.lower()] = environ_getter(key) del key
  130. 130. • urllib.urlopen socks
  131. 131. Monkey Patch
  132. 132. import httplib orig_connect = httplib.HTTPConnection.connect def _patched_connect(self): if HOSTS_BLOCKED.match(self.host): return _connect_via_socks_proxy(self) else: return orig_connect(self) def _connect_via_socks_proxy(self): ... httplib.HTTPConnection.connect = _patched_connect
  133. 133. Python
  134. 134. Python • Pythonic!
  135. 135. Python • Pythonic! • Avoid gotchas http://www.ferg.org/projects/python_gotchas.html
  136. 136. Python • Pythonic! • Avoid gotchashttp://www.ferg.org/projects/python_gotchas.html • Unicode / Character Encoding
  137. 137. Python • Pythonic! • Avoid gotchas http://www.ferg.org/projects/python_gotchas.html • Unicode / Character Encoding • GIL (Global Interpreter Lock)
  138. 138. Python • Pythonic! • Avoid gotchas http://www.ferg.org/projects/python_gotchas.html • Unicode / Character Encoding • GIL (Global Interpreter Lock) • Garbage Collection
  139. 139. • :Vim / Emacs / Ulipad • : subversion / mercurial / git • wiki/ / : Trac • : Bitten
  140. 140. Python Implementations
  141. 141. Python Implementations • CPython http://www.python.org/
  142. 142. Python Implementations • CPython http://www.python.org/ • Unlanden-Swallow http://code.google.com/p/unladen-swallow/
  143. 143. Python Implementations • CPython http://www.python.org/ • Unlanden-Swallow http://code.google.com/p/unladen-swallow/ • Stackless Python http://www.stackless.com/
  144. 144. Python Implementations • CPython http://www.python.org/ • Unlanden-Swallow http://code.google.com/p/unladen-swallow/ • Stackless Python http://www.stackless.com/ • IronPython http://ironpython.net/
  145. 145. Python Implementations • CPython http://www.python.org/ • Unlanden-Swallow http://code.google.com/p/unladen-swallow/ • Stackless Python http://www.stackless.com/ • IronPython http://ironpython.net/ • Jython http://www.jython.org/
  146. 146. Python Implementations • CPython http://www.python.org/ • Unlanden-Swallow http://code.google.com/p/unladen-swallow/ • Stackless Python http://www.stackless.com/ • IronPython http://ironpython.net/ • Jython http://www.jython.org/ • PyPy http://pypy.org/
  147. 147. Q &A

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