Exhibition of Atrocity

1.
Exhibition of Atrocity Mike Pirnat // PyCon 2011 @mpirnat

3.
Disclaimer

4.
Lies, Damn Lies,and Hungarian Notation

5.
Good Intentions

6.
Good Intentions • strFirstName

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Good Intentions • strFirstName •intYear

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Good Intentions • strFirstName •intYear • blnSignedIn

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Good Intentions • strFirstName •intYear • blnSignedIn • ﬂtTaxRate

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Good Intentions • strFirstName •intYear • blnSignedIn • ﬂtTaxRate • lstProducts

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Good Intentions • strFirstName •intYear • blnSignedIn • ﬂtTaxRate • lstProducts • dctParams

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Silliness

13.
Silliness • lctResults ??

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Silliness • lctResults ?? •objMyReallyLongName ??

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Silliness • lctResults ?? •objMyReallyLongName ?? • objMRLN ??

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Silliness • lctResults ?? •objMyReallyLongName ?? • objMRLN ?? • varValue ??

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Silliness • lctResults ?? •objMyReallyLongName ?? • objMRLN ?? • varValue ?? • blnMagic ??

18.
LIES

19.
LIES • strCustomerNumber

20.
LIES • strCustomerNumber • blnFoo= 'N'

21.
LIES • strCustomerNumber • blnFoo= 'N' • ‘NoneType’ object has no attribute...

22.
Crimes Against PEP-8

23.
class MyGiganticUglyClass(object): defiUsedToWriteJava(self,x,y = 42): blnTwoSpacesAreMoreEfficient = 1 while author.tragicallyConfused(): print "Three spaces FTW roflbbq!!1!" if (new_addition): four_spaces_are_best = True if (multipleAuthors or peopleDisagree): print "tabs! spaces are so mainstream" return ((pain) and (suffering))

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from regrets import unfortunate_choices class AnotherBadHabit(object): short_name = 'foo' much_longer_name = 'bar' def __init__(self, x, y, z): self.x = x self.y = y self.z_is_a_silly_name = z self.came_later = 42 self.leftover = ‘timewaster’ self.dictionary = { 'foo' : 'bar', 'bar' : 'baz', 'baz' : 'quux', }

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34.
A Twisty Mazeof Single-Character Variables, All Alike

35.
f.write(string.join(map(lambda x,y=self.__dicProfiles,z=strPy:"%0.3s %s: %s:(%s)" %(z,x,y[x][0],y[x] [1]),self.__dicProfiles.keys()),'n') +'n')

36.
#!/usr/bin/env python import os,sys C=os.chdir S=os.system M=os.mkdir J=os.path.join A=os.path.abspath D=os.path.dirname E=os.path.exists W=sys.stdout.write V=sys.argv X=sys.exit ERR=lambdam:W(m+"n") PRNT=lambda m:W(m+"n") assert len(V)==2,"you must provide a sandbox name" SB=V[1] H=A(D(__file__)) SBD=J(D(H),SB) C(SBD) PST=J(SBD,'bin/paster') VAR=J(SBD,'var') ETC=J(SBD,'etc') S("mkdir -p "+VAR) PRNT("restarting "+SB) CMD=";".join(['source %s'%J(SBD,'bin/activate'),PST+" serve --daemon --pid- file=%s/sandbox.pid --log-file=%s/sandbox.log %s/sandbox.ini start"% (VAR,VAR,ETC)]) PRNT(CMD) S(CMD) PRNT("All done!") X(0)

37.
#!/usr/bin/env python import os,sys C=os.chdir S=os.system M=os.mkdir J=os.path.join A=os.path.abspath D=os.path.dirname E=os.path.exists W=sys.stdout.write V=sys.argv X=sys.exit ERR=lambdam:W(m+"n") PRNT=lambda m:W(m+"n") assert len(V)==2,"you must provide a sandbox name" SB=V[1] H=A(D(__file__)) SBD=J(D(H),SB) C(SBD) PST=J(SBD,'bin/paster') VAR=J(SBD,'var') ETC=J(SBD,'etc') S("mkdir -p "+VAR) PRNT("restarting "+SB) CMD=";".join(['source %s'%J(SBD,'bin/activate'),PST+" serve --daemon --pid- file=%s/sandbox.pid --log-file=%s/sandbox.log %s/sandbox.ini start"% (VAR,VAR,ETC)]) PRNT(CMD) S(CMD) PRNT("All done!") X(0)

38.
Lambdas, Lambdas Everywhere

40.
lstRollOut = lstRollOut+ filter(lambda x: x[-1] == '0', filter(lambda x: x != '0|0', lstMbrSrcCombo))

41.
lstRollOut = lstRollOut+ filter(lambda x: x[-1] == '0', filter(lambda x: x != '0|0', lstMbrSrcCombo)) if not filter(lambda lst, sm=sm: sm in lst, map(lambda x, dicA=dicA: dicA.get(x, []), lstAttribute)):

43.
_make_keys = lambdacc, pm: tuple(map(lambda m, c=cc: ("%s.%s" % (c, m), m), pm))

44.
_make_keys = lambdacc, pm: tuple(map(lambda m, c=cc: ("%s.%s" % (c, m), m), pm)) return [map(lambda l: l[0], lstResults),map(lambda l: l[1], lstResults)]

45.
_make_keys = lambdacc, pm: tuple(map(lambda m, c=cc: ("%s.%s" % (c, m), m), pm)) return [map(lambda l: l[0], lstResults),map(lambda l: l[1], lstResults)] sum = lambda lst: lst and reduce(lambda x, y: x + y, lst) or 0

46.
_make_keys = lambdacc, pm: tuple(map(lambda m, c=cc: ("%s.%s" % (c, m), m), pm)) return [map(lambda l: l[0], lstResults),map(lambda l: l[1], lstResults)] sum = lambda lst: lst and reduce(lambda x, y: x + y, lst) or 0 assert reduce(lambda x,y: x or y, [z.id == event.id for z in events])

47.
The List Comprehension that Ate Cincinnati

49.
lstCrumb = [yfor y in [x.replace('"','') for x in lstCrumb] if y]

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lstCrumb = [yfor y in [x.replace('"','') for x in lstCrumb] if y] return [dict(x) for x in [zip(lstKeys,x) for x in lstValues]]

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lstCrumb = [yfor y in [x.replace('"','') for x in lstCrumb] if y] return [dict(x) for x in [zip(lstKeys,x) for x in lstValues]] prop_list = [FilterProp(prop='P_EXCLUDED', data='_'.join([i,j,k])) for i in prop_data[0] for j in prop_data[1] for k in prop_data[2]]

52.
def feedparser_entries_to_RSSItems(entries): rss_items = [PyRSS2Gen.RSSItem( title = x.get('title','Untitled'), link = x.link, description = x.summary, guid = x.link, pubDate = datetime.datetime( x.modified_parsed[0], x.modified_parsed[1], x.modified_parsed[2], x.modified_parsed[3], x.modified_parsed[4], x.modified_parsed[5])) for x in entries] return rss_items

53.
def feedparser_entries_to_RSSItems(entries): rss_items = [rss_item(entry) for entry in entries] return rss_items

54.
The Beast witha Thousand Elifs

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def do_awesome_stuff(): ... if site.isSiteOne(): ... elif site.isSiteTwo(): ... elif site.getSite() in ['site3', 'site4']: ... elif site.isSiteFive(): ... else: ... ...

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def strategy1(): ... def strategy2(): ... site_strategies = { 'site1': strategy1, 'site2': strategy2, ... } def do_awesome_stuff(): which_one = ... strategy = site_strategies[which_one] strategy()

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def do_awesome_stuff(strategy): ... strategy() ...

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def do_awesome_stuff(strategy): ... strategy() ...

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class Foo(object): def __init__(self, strategy): self.strategy = strategy def do_awesome_stuff(self): ... self.strategy() ...

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class Foo(object): def __init__(self, strategy): self.strategy = strategy def do_awesome_stuff(self): ... self.strategy() ...

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class Foo(object): @inject(strategy=IStrategy) def __init__(self, strategy): self.strategy = strategy def do_awesome_stuff(self): ... self.strategy() ...

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The Malignant Menace of Mutable Keyword Argument Defaults

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def set_reminders(self, event,reminders=[]): ...

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def set_reminders(self, event,reminders=[]): ...

73.
• Extra reminderscame from other users' requests...

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• Extra reminderscame from other users' requests... • What if this was really sensitive data?

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def set_reminders(self, event,reminders=None): reminders = reminders or [] ...

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DCT_BRAND_REMINDERS = { SITE_X: [ HOLIDAYS: [Reminder(...), ...], OTHER: [Reminder(...), ...], CUSTOM: [Reminder(...), ...], ], ... } ... class BrandWrangler(object): ... def get_default_reminders(self, brand): return DCT_BRAND_REMINDERS.get(brand, {})

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DCT_BRAND_REMINDERS = { SITE_X: [ HOLIDAYS: [Reminder(...), ...], OTHER: [Reminder(...), ...], CUSTOM: [Reminder(...), ...], ], ... } ... class BrandWrangler(object): ... def get_default_reminders(self, brand): return copy.deepcopy( DCT_BRAND_REMINDERS.get(brand, {}))

82.
DCT_BRAND_REMINDERS = { SITE_X: [ HOLIDAYS: [Reminder(...), ...], OTHER: [Reminder(...), ...], CUSTOM: [Reminder(...), ...], ], ... } ... class BrandWrangler(object): ... def get_default_reminders(self, brand): return copy.deepcopy( DCT_BRAND_REMINDERS.get(brand, {}))

83.
Java PTSD: Getters andSetters

84.
class InviteEvent(object): ... def getEventNumber(self): return self._intEventNumber ... def setEventNumber(self, x): self._intEventNumber = int(x) ... event.setEventNumber(10) print event.getEventNumber()

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class InviteEvent(object): ... @property def event_number(self): return self._event_number @event_number.setter def _set_event_number(self, x): self._intEventNumber = int(x) ... event.event_number = 10 print event.event_number

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DTO Bondage

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class Calendar(DataObject): calendar_id = None user_id = None label = None description = None

93.
class DataObject(object): def __new__(cls, *args, **kwargs): obj = object.__new__(cls) for key, value in cls.__dict__.items(): if not callable(value) and not hasattr(value, '__get__') and not key.startswith('_'): setattr(obj, key, value) return obj

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class StrictDataObject(DataObject): def __init__(self, **kwargs): for key, value in kwargs.items(): if hasattr(self, key): setattr(self, key, value) else: raise AttributeError( 'key %r must be predefined ' 'at the class level' % key)

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class MutantDataObject(StrictDataObject): def __new__(cls, *args, **kwargs): new_object = object.__new__(cls) for c in cls.__mro__[::-1]: update_friendly_dict = _get_update_friendly_dict_from_class_dictproxy(c.__dict__) new_object.update(update_friendly_dict) return new_object def __init__(self, **kwargs): deferred = {} clean = {} for key, value in kwargs.items(): if hasattr(self, key): clean[key] = value else: deferred[key] = value super(MutantDataObject, self).__init__(**clean) self.update(deferred) ...

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time passes...

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Time to instantiate100000 1.9 1.8 1.7 1.6 1.5 DataObject StrictDataObject

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Time to instantiate100000 15 11.25 7.5 3.75 0 DataObject StrictDataObject MutantDataObject

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class DataObject(object): _mutables = None __metaclass__ = DataObjectMeta def __new__(cls, **kwargs): obj = object.__new__(cls) for name, default_func in cls._mutables: if name not in kwargs: setattr(obj, name, default_func()) return obj def __init__(self, **kwargs): for name, value in kwargs.iteritems(): setattr(self, name, value)

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class DataObjectMeta(type): def __new__(meta, classname, bases, classdict): mutables = find_mutables(classdict, bases) classdict['_mutables'] = mutables return type.__new__(meta, classname, bases, classdict) def find_mutables(classdict, bases): def create_default(name, value): return name, lambda: copy.copy(value) found_mutables = set() mutables = set() for name, value in classdict.items(): if (not name.startswith('__') and not callable(value) and not hasattr(value, '__get__') and isinstance(value, (list, dict))): if not name in found_mutables: found_mutables.add(name) mutables.add(create_default(name, value)) del classdict[name] for base in bases: if hasattr(base, '_mutables'): for name, value in base._mutables: if not name in found_mutables: found_mutables.add(name) mutables.add((name, value)) return frozenset(mutables)

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Time to instantiate100000 15 11.25 7.5 3.75 0 DataObject StrictDataObject MutantDataObject Metaclass DataObject

110.
God Objects, GodMethods, and The Mile-Long Club

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class CardOrderPage(WebPage): ... ~2900 lines 69 methods __init__ ~85 lines _populateFromUPD ~200 lines _populateMisc ~200 lines _completeOrder ~300 lines _buildOrderDct ~300 lines _redirectTo ~200 lines

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class MemberOrderPage(WebPage): ... ~2400 lines 58 methods __init__ ~90 lines processInit ~160 lines processSubmit ~120 lines _processOrder ~220 lines _processVirtualOrder ~110 lines _createUCSOrder ~240 lines _sendWelcomeEmail ~120 lines

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class Session(object): ... ~1000 lines 79 methods, mostly small __init__ ~180 lines _buildReturnURL ~125 lines

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def update_everything(...): ...

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def update_everything(...): ... def do_everything(...): ...

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def update_everything(...): ... def do_everything(...): ... def go(...): ...

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Refactor

119.
The Seductive Lure of Global State

120.
# gvars.py dctEnv =None objSession = None objWebvars = None objHeaders = None objUserAgent = None

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from col.web importgvars ... if gvars.objSession.hasSomething(): ... if gvars.objWebvars.get('foo') == 'bar': ... strUserName = gvars.objSession.objCustomer.getName()

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• Highly convenientwhen writing front-end website code

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• Highly convenientwhen writing front-end website code • Highly painful when doing anything else (scripts, cron jobs, back-end systems)

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• Highly convenientwhen writing front-end website code • Highly painful when doing anything else (scripts, cron jobs, back-end systems) • Any code that uses it is not reusable outside the website context without extensive faking

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• Highly convenientwhen writing front-end website code • Highly painful when doing anything else (scripts, cron jobs, back-end systems) • Any code that uses it is not reusable outside the website context without extensive faking • Safety issues/data leakage

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Breaking the Law (of Demeter)

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gvars.objSession.objCustomer.objMemberStatus .isPAID()

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gvars.objSession.objCustomer.objMemberStatus .isPAID() if gvars.dctEnv['session'].getCustomer() .isSignedIn():

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gvars.objSession.objCustomer.objMemberStatus .isPAID() if gvars.dctEnv['session'].getCustomer() .isSignedIn(): current_url = self.objSession._getCurrentURL()

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gvars.objSession.objCustomer.objMemberStatus .isPAID() if gvars.dctEnv['session'].getCustomer() .isSignedIn(): current_url = self.objSession._getCurrentURL() return (iEvent._objGuestList.getGuestList()[0] .getEventSequence())

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class MyController(BaseController): @require_auth(...) def my_action(self, request): ... class require_auth(object): ... def __call__(self, function): def decorated(controller, request, *args, **kwargs): user = controller.user if user.signed_in: ... ... return decorated

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class MyController(BaseController): @require_auth(...) def my_action(self, request): ... class require_auth(object): ... def __call__(self, function): def decorated(controller, request, *args, **kwargs): user = controller.user if user.signed_in: ... ... return decorated

135.
The Diaper Pattern

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def get_important_object(): try: data = talk_to_database(...) return ImportantObject(data) except: pass foo = get_important_object(...) foo.do_something_important()

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def get_important_object(): data = talk_to_database(...) return ImportantObject(data) foo = get_important_object(...) foo.do_something_important()

140.
Creative Ways to Break the Build

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class DuckPuncher(object): def __init__(...): ... def setup(...): ... def teardown(...): ... def punch(...): ... def hug(...): ... def with_setup(self, func): def test_func_wrapper(*args, **kwargs): self.setup() ret = func(*args, **kwargs) self.teardown() return ret test_func_wrapper = wraps(func)(test_func_wrapper) return test_func_wrapper

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class DuckPuncher(object): def __init__(...): ... def setup(...): ... def teardown(...): ... def punch(...): ... def hug(...): ... def with_setup(self, func): def test_func_wrapper(*args, **kwargs): self.setup() ret = func(*args, **kwargs) self.teardown() return ret test_func_wrapper = wraps(func)(test_func_wrapper) return test_func_wrapper

143.
class DuckPuncher(object): def __init__(...): ... def setup(...): ... def teardown(...): ... def punch(...): ... def hug(...): ... def with_setup(self, func): def test_func_wrapper(*args, **kwargs): self.setup() try: ret = func(*args, **kwargs) finally: self.teardown() return ret test_func_wrapper = wraps(func)(test_func_wrapper) return test_func_wrapper

144.
class DuckPuncher(object): def __init__(...): ... def setup(...): ... def teardown(...): ... def punch(...): ... def hug(...): ... def with_setup(self, func): def test_func_wrapper(*args, **kwargs): self.setup() try: ret = func(*args, **kwargs) finally: self.teardown() return ret test_func_wrapper = wraps(func)(test_func_wrapper) return test_func_wrapper

145.
from mock importpatch class TestMyThing(...): @patch(‘__builtin__.open’): def test_writes_files(self, mock_open): ...

146.
Adventures in Wheel Reinvention

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• log

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• log • xlog

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• log • xlog • simplelog

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• log • xlog • simplelog • superlog

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• log • xlog • simplelog • superlog • pylogger

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• log • xlog • simplelog • superlog • pylogger • prettylog

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• log • logging (not stdlib!) • xlog • simplelog • superlog • pylogger • prettylog

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• log • logging (not stdlib!) • xlog • logmanager • simplelog • superlog • pylogger • prettylog

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• log • logging (not stdlib!) • xlog • logmanager • simplelog • logging (stdlib!) • superlog • pylogger • prettylog

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• log • logging (not stdlib!) • xlog • logmanager • simplelog • logging (stdlib!) • superlog • logwrangler • pylogger • prettylog

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• log • logging (not stdlib!) • xlog • logmanager • simplelog • logging (stdlib!) • superlog • logwrangler • pylogger • agi.log • prettylog

159.
tl;dr • Hungarian notationBAD • PEP-8 GOOD • Unclean code BAD • Use existing tools GOOD • Weird build breaking BAD

160.
Things to Explore

161.
Things to Explore •Clean Code: http://ASIN.cc/~11GQo

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Things to Explore •Clean Code: http://ASIN.cc/~11GQo • http://code.google.com/p/snake-guice/

163.
Things to Explore •Clean Code: http://ASIN.cc/~11GQo • http://code.google.com/p/snake-guice/ • http://www.voidspace.org.uk/python/mock/

166.
Links • Twitter: @mpirnat •Blog: http://mike.pirnat.com • Inspiration: • Gary Numan: http://youtu.be/Oj2PR9CI9xY • Joy Division: http://youtu.be/5AqeqAQ1ILI • Hyperbole and a Half: http://hyperboleandahalf.blogspot.com/2010/06/ this-is-why-ill-never-be-adult.html

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