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Python 于Web 2.0网站的应用 (QCon Beijing 2010)

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  • 案例四的两种实现结果是不是不一样?
    实现1会把self.feeds * limit个entry按entry.id倒序排列
    实现2是依此取各个self.feeds的iterator的第n个
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  • 1. Python Web 2.0 QCon Beijing 2010http://www.flickr.com/photos/arnolouise/2986467632/
  • 2. About Me• Python• 2002 Python• 2004 Python• http://www.douban.com/ people/hongqn/• hongqn@douban.com• http://twitter.com/hongqn
  • 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. Languages in C 27% Javascript 12% C++ Python 3% 58% (Pyrex/R/Erlang/Go/Shell) 1%
  • 5. Why Python?
  • 6. • Hello World: 1
  • 7. • Hello World: 1• :1
  • 8. • Hello World: 1• :1• :1
  • 9. • Hello World: 1• :1• :1• :3
  • 10. : 13
  • 11. : 13import osfrom collections import defaultdictd = 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. •• Pythonic
  • 13. • 1. svn ci 2. svn up 3. restart
  • 14. • Web•••
  • 15. • Battery Included: 200+• PyPI: 9613 packages currently• / / / / / / /...• easily extensible
  • 16. Python
  • 17. Python
  • 18. PythonJust kidding :-p
  • 19. Web Server
  • 20. Web Server• python -m SimpleHTTPServer
  • 21. Web Server• python -m SimpleHTTPServer
  • 22. web.py http://webpy.org/import weburls = ( /(.*), 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. Flask http://flask.pocoo.org/import flask import Flaskapp = Flask(__name__)@app.route("/<name>")def hello(name): if not name: name = World return Hello, + name + !if __name__ == "__main__": app.run()
  • 24. WSGI http://www.python.org/dev/peps/pep-0333/
  • 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. doctestdef cube(x): """ >>> cube(10) 1000 """ return x * xdef _test(): import doctest doctest.testmod()if __name__ == "__main__": _test()
  • 27. nose http://somethingaboutorange.com/mrl/projects/nose/from cube import cubedef test_cube(): result = cube(10) assert result == 1000
  • 28. numpy http://numpy.scipy.org/>>> from numpy import *>>> A = arange(4).reshape(2, 2)>>> Aarray([[0, 1], [2, 3]])>>> dot(A, A.T)array([[ 1, 3], [ 3, 13]])
  • 29. ipython http://numpy.scipy.org/$ ipython -pylabIn [1]: X = frange(0, 10, 0.1)In [2]: Y = [sin(x) for x in X]In [3]: plot(X, Y)
  • 30. ipython http://numpy.scipy.org/$ ipython -pylabIn [1]: X = frange(0, 10, 0.1)In [2]: Y = [sin(x) for x in X]In [3]: plot(X, Y)
  • 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. Pyrex/Cythoncdef extern from "math.h" double sin(double)cdef double f(double x): return sin(x*x)
  • 33. Pythonic
  • 34. >>> import thisThe Zen of Python, by Tim Peters http://bit.ly/pyzencnBeautiful 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 arent special enough tobreak the rules.  Although practicality beats purity.Errors should never pass silently.Unless explicitly silenced.  
  • 35. In the face of ambiguity, refuse thetemptation to guess.There should be one-- andpreferably only one --obvious wayto do it.Although that way may not be Pythonobvious at first unless youre Dutch.  Now is better than never.Although never is often better than*right* now.  If the implementation is hard toexplain, its a bad idea.If the implementation is easy to  explain, it may be a good idea.Namespaces are one honking greatidea -- lets do more of those!
  • 36. Simple is better than complexclass HelloWorld{ public static void main(String args[]) { System.out.println("Hello World!"); }}
  • 37. Simple is better than complex print "Hello World!"
  • 38. Readability counts
  • 39. Readability counts• {} end
  • 40. Readability counts• {} end• (except "@" for decorators)
  • 41. Readability counts• {} end• (except "@" for decorators)if limit is not None and len(ids)>limit: ids = random.sample(ids, limit)
  • 42. TOOWTDI• There (should be) Only One Way To Do It.• vs. Perlish TIMTOWTDI (There Is More Than One Way To Do It)
  • 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. 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. 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. 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. 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. http://twitter.com/robbinfan/status/9879724095http://twitter.com/hongqn/status/9883515681
  • 49. Python Chttp://www.flickr.com/photos/nicksieger/281055485/ http://www.flickr.com/photos/nicksieger/281055530/
  • 50. Rubyhttp://www.flickr.com/photos/nicksieger/280661836/
  • 51. Javahttp://www.flickr.com/photos/nicksieger/280662707/
  • 52. Python
  • 53. • svn
  • 54. • svn• ( list)
  • 55. • svn• ( list)• +
  • 56. • svn• ( list)• +• parser
  • 57. config.pyMEMCACHED_ADDR = [localhost:11211]from local_config import *
  • 58. config.pyMEMCACHED_ADDR = [localhost:11211]from local_config import * local_config.py MEMCACHED_ADDR = [ frodo:11211, sam:11211, pippin:11211, merry:11211, ]
  • 59. config.pyMEMCACHED_ADDR = [localhost:11211]from local_config import * .py local_config.py exec MEMCACHED_ADDR = [ frodo:11211, sam:11211, pippin:11211, merry:11211, ]
  • 60.
  • 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. 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. decoratordef print_before_exec(func): def _(*args, **kwargs): print "decorated" return func(*args, **kwargs) return _@print_before_execdef double(x): print x*2double(10)
  • 64. decoratordef print_before_exec(func): def _(*args, **kwargs): print "decorated" return func(*args, **kwargs) return _ decorated@print_before_execdef double(x): 20 print x*2double(10)
  • 65. class check_permission(object): def __init__(self, action, msg=None): self.action = action self.msg = msg def __call__(self, func): def _(ui, *args, **kwargs): f = getattr(ui.perm_obj, can_ + action) if f(req.user): return func(ui, *args, **kwargs) raise BadPermission(ui.perm_obj, self.action, self.msg) return _
  • 66. class check_permission(object): def __init__(self, action, msg=None): self.action = action self.msg = msg def __call__(self, func): def _(ui, *args, **kwargs): f = getattr(ui.perm_obj, can_ + action) if f(req.user): return func(ui, *args, **kwargs) raise BadPermission(ui.perm_obj, self.action, self.msg) return _
  • 67. class check_permission(object): def __init__(self, action, msg=None): self.action = action self.msg = msg def __call__(self, func): def _(ui, *args, **kwargs): f = getattr(ui.perm_obj, can_ + action) if f(req.user): return func(ui, *args, **kwargs) raise BadPermission(ui.perm_obj, self.action, self.msg) return _
  • 68. class check_permission(object): def __init__(self, action, msg=None): self.action = action self.msg = msg def __call__(self, func): def _(ui, *args, **kwargs): f = getattr(ui.perm_obj, can_ + action) if f(req.user): return func(ui, *args, **kwargs) raise BadPermission(ui.perm_obj, self.action, self.msg) return _
  • 69. class check_permission(object): def __init__(self, action, msg=None): self.action = action self.msg = msg def __call__(self, func): def _(ui, *args, **kwargs): f = getattr(ui.perm_obj, can_ + action) if f(req.user): return func(ui, *args, **kwargs) raise BadPermission(ui.perm_obj, self.action, self.msg) return _
  • 70. class check_permission(object): def __init__(self, action, msg=None): self.action = action self.msg = msg def __call__(self, func): def _(ui, *args, **kwargs): f = getattr(ui.perm_obj, can_ + action) if f(req.user): return func(ui, *args, **kwargs) raise BadPermission(ui.perm_obj, self.action, self.msg) return _
  • 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.
  • 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. @asyncdef 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. def async(func): mod = sys.modules[func.__module__] fname = origin_ + func.__name__ mod[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[fname](*a, **kw)
  • 76. def async(func): mod = sys.modules[func.__module__] fname = origin_ + func.__name__ mod[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[fname](*a, **kw)
  • 77. def async(func): mod = sys.modules[func.__module__] fname = origin_ + func.__name__ mod[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[fname](*a, **kw)
  • 78. def async(func): mod = sys.modules[func.__module__] fname = origin_ + func.__name__ mod[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[fname](*a, **kw)
  • 79. def async(func): mod = sys.modules[func.__module__] fname = origin_ + func.__name__ mod[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[fname](*a, **kw)
  • 80. def async(func): mod = sys.modules[func.__module__] fname = origin_ + func.__name__ mod[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[fname](*a, **kw)
  • 81. def async(func): mod = sys.modules[func.__module__] fname = origin_ + func.__name__ mod[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[fname](*a, **kw)
  • 82. def async(func): mod = sys.modules[func.__module__] fname = origin_ + func.__name__ mod[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[fname](*a, **kw)
  • 83. • cache (SQL, , etc)
  • 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. @cache(latest_review_id)def get_latest_review_id(): return exc_sql("select max(id) from review")
  • 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. 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. cache keydef 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. 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. 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. 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. 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. 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. 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. 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. 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. 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. • feed feed entry_id
  • 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. 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. 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. 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. 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. iterator and generatordef fib(): x, y = 1, 1 while True: yield x x, y = y, x+ydef 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 numberprint sum(odd(less_than(fib(), 4000000)))
  • 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. class Feed(object): def iter_entries(self): start_id = sys.maxint while True: entry_ids = exc_sqls("select id from entry wherefeed_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. class Feed(object): def iter_entries(self): start_id = sys.maxint while True: entry_ids = exc_sqls("select id from entry wherefeed_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. class Feed(object): def iter_entries(self): start_id = sys.maxint while True: entry_ids = exc_sqls("select id from entry wherefeed_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. class Feed(object): def iter_entries(self): start_id = sys.maxint while True: entry_ids = exc_sqls("select id from entry wherefeed_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. class Feed(object): def iter_entries(self): start_id = sys.maxint while True: entry_ids = exc_sqls("select id from entry wherefeed_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. class Feed(object): def iter_entries(self): start_id = sys.maxint while True: entry_ids = exc_sqls("select id from entry wherefeed_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 -5class 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. class Feed(object): def iter_entries(self): start_id = sys.maxint while True: entry_ids = exc_sqls("select id from entry wherefeed_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 =0class 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. decorator generator
  • 114.
  • 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 = siguser = User(1002211, hongqn, hongqn, " ")
  • 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. cPickle vs. marshal$ python -m timeit -s > from user import user> from cPickle import dumps, loads> s = dumps(user, 2) > loads(s) 7100000 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. cPickle vs. marshal$ python -m timeit -s > from user import user> from cPickle import dumps, loads> s = dumps(user, 2) > loads(s) 7100000 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. 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: 129marshal: 74 43%
  • 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: 129marshal: 74 43%
  • 121. namedtuplefrom collections import namedtupleUser = namedtuple(User, id username screen_name sig)user = User(1002211, hongqn, hongqn, sig=" ")user.username-> hongqn
  • 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. from operator import itemgetterclass 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. Warning!
  • 125. • request.get_environ(key) • e.g. request.get_environ(REMOTE_ADDR) --> request.remote_addr
  • 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. 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. 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. 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. • urllib.urlopen socks
  • 131. Monkey Patch
  • 132. import httpliborig_connect = httplib.HTTPConnection.connectdef _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. Python
  • 134. Python• Pythonic!
  • 135. Python• Pythonic!• Avoid gotchas http://www.ferg.org/projects/python_gotchas.html
  • 136. Python• Pythonic!• Avoid gotchashttp://www.ferg.org/projects/python_gotchas.html• Unicode / Character Encoding
  • 137. Python• Pythonic!• Avoid gotchas http://www.ferg.org/projects/python_gotchas.html• Unicode / Character Encoding• GIL (Global Interpreter Lock)
  • 138. Python• Pythonic!• Avoid gotchas http://www.ferg.org/projects/python_gotchas.html• Unicode / Character Encoding• GIL (Global Interpreter Lock)• Garbage Collection
  • 139. • :Vim / Emacs / Ulipad• : subversion / mercurial / git• wiki/ / : Trac• : Bitten
  • 140. PythonImplementations
  • 141. Python Implementations• CPython http://www.python.org/
  • 142. Python Implementations• CPython http://www.python.org/• Unlanden-Swallow http://code.google.com/p/unladen-swallow/
  • 143. Python Implementations• CPython http://www.python.org/• Unlanden-Swallow http://code.google.com/p/unladen-swallow/• Stackless Python http://www.stackless.com/
  • 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. 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. 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. Q &A