Slides from my PyCon 2011 talk, "Exhibition of Atrocity," a confessional of my sins against the Python programming language. Abstract: http://us.pycon.org/2011/schedule/presentations/138/ Video: http://www.pycon.tv/#/video/49

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

7. Good Intentions
• strFirstName
• intYear

8. Good Intentions
• strFirstName
• intYear
• blnSignedIn

9. Good Intentions
• strFirstName
• intYear
• blnSignedIn
• fltTaxRate

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

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

12. Silliness

13. Silliness
• lctResults ??

14. Silliness
• lctResults ??
• objMyReallyLongName ??

15. Silliness
• lctResults ??
• objMyReallyLongName ??
• objMRLN ??

16. Silliness
• lctResults ??
• objMyReallyLongName ??
• objMRLN ??
• varValue ??

17. 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):
def iUsedToWriteJava(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))

24. class MyGiganticUglyClass(object):
def iUsedToWriteJava(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))

25. class MyGiganticUglyClass(object):
def iUsedToWriteJava(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))

26. class MyGiganticUglyClass(object):
def iUsedToWriteJava(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))

27. class MyGiganticUglyClass(object):
def iUsedToWriteJava(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))

28. class MyGiganticUglyClass(object):
def iUsedToWriteJava(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))

29. class MyGiganticUglyClass(object):
def iUsedToWriteJava(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))

30. class MyGiganticUglyClass(object):
def iUsedToWriteJava(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))

31. 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',
}

32. 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',
}

33. 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',
}

34. A Twisty Maze of
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=lambda m: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=lambda m: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 = lambda cc, pm:
tuple(map(lambda m, c=cc: ("%s.%s" % (c,
m), m), pm))

44. _make_keys = lambda cc, 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 = lambda cc, 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 = lambda cc, 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 = [y for y in [x.replace('"','') for x in
lstCrumb] if y]

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

51. lstCrumb = [y for 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 with a
Thousand Elifs

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

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

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

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

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

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

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

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

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

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

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

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

67. The Malignant Menace
of Mutable Keyword
Argument Defaults

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

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

73. • Extra reminders came from other users'
requests...

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

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

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

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

78. 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, {})

79. 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, {})

80. 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, {})

81. 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 and Setters

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

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

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

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

88. 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

89. 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

90. 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

91. DTO Bondage

92. 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

94. 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

95. 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

96. 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)

97. 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)

98. 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)

99. 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)

100. 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)
...

101. time passes...

102. Time to instantiate 100000
1.9
1.8
1.7
1.6
1.5
DataObject StrictDataObject

103. Time to instantiate 100000
15
11.25
7.5
3.75
0
DataObject StrictDataObject MutantDataObject

104. 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)

105. 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)

106. 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)

107. 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)

108. 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)

109. Time to instantiate 100000
15
11.25
7.5
3.75
0
DataObject StrictDataObject MutantDataObject Metaclass DataObject

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

111. 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

112. 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

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

115. def update_everything(...):
...

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

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

118. Refactor

119. The Seductive Lure
of Global State

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

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

123. • Highly convenient when writing front-end
website code

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

125. • Highly convenient when 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

126. • Highly convenient when 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

127. Breaking the Law
(of Demeter)

129. gvars.objSession.objCustomer.objMemberStatus
.isPAID()

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

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

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

133. 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

134. 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

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

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

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

139. 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

141. 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

142. 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 import patch
class TestMyThing(...):
@patch(‘__builtin__.open’):
def test_writes_files(self, mock_open):
...

146. Adventures in Wheel
Reinvention

148. • log

149. • log
• xlog

150. • log
• xlog
• simplelog

151. • log
• xlog
• simplelog
• superlog

152. • log
• xlog
• simplelog
• superlog
• pylogger

153. • log
• xlog
• simplelog
• superlog
• pylogger
• prettylog

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

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

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

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

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

159. tl;dr
• Hungarian notation BAD
• 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

162. 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