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1. Inports
2. Indentation
3. Techniques

• 1.1 Split imports into 3 categories (stdlib, 3rdparty, internal imports), relative imports should be the last. Try to keep them sorted.

  importdatetimeimportloggingfromdjango.utilsimporttimezonefromdjango.utils.translationimportugettext_lazyas_fromdjango.confimportsettingsfromdjango_states.machineimportStateMachine,StateDefinition,StateGroup,StateTransitionfromdjango_states.exceptionsimportTransitionValidationErrorfromourapp.notifications.handlersimportNOTIFICATION_METHODfromourapp.notificationsimportnotifiersfromourapp.module_a.providerimportTrustedfromourapp.activation.modelsimportXOrderfromourapp.porting.utilsimportget_closest_wish_datefrom .modelsimportInportfrom .utilsimportadd_inport_s3

• 1.2 Use imports for packages and modules only, if it is possible.

  importdatetime# never: from datetime import datetime or similarimportlogging# never: from logging import getLoggerimportmock# never from mock import Mockimportrandomimportuuidimportbson# never from bson import ObjectIdfromdjango.utilsimporttimezone# never: from django.utils.timezone import now

• 1.3 If import exceeded line length limit, format it like that:

  fromourapp.porting.tasksimport (task_a,task_b,task_c,# <- comma here)

• 2.1function calls

  abc=qwe(dsadsa(product.to_dict(),cls=DecimalEncoder,mimetype='application/json'))# badabc=qwe(dsadsa(product.to_dict(),cls=DecimalEncoder,mimetype='application/json'))# badabc=qwe(dsadsa(product.to_dict(),cls=DecimalEncoder,mimetype='application/json'))# badabc=qwe(dsadsa(product.to_dict(),cls=DecimalEncoder,mimetype='application/json',# <- comma here))# OKabc=qwe(dsadsa(product.to_dict(),cls=DecimalEncoder,mimetype='application/json',# <- comma here    ))# could be too# especially when qwe has one aditional keyword parameter:abc=qwe(dsadsa(product.to_dict(),cls=DecimalEncoder,mimetype='application/json',# <- comma here    ),# <- comma heredupa=2,# <- comma here)# OK

• 2.2dict class

  # badabc=dict(abc=2,cde=5,mama='tata',tata='mama',raz=1,dwa=2)# badabc=dict(abc=2,cde=5,mama='tata',tata='mama',raz=1,dwa=2)# badabc=dict(abc=2,cde=5,mama='tata',tata='mama',raz=1,dwa=2)# badabc=dict(abc=2,cde=5,mama='tata',tata='mama',raz=1,dwa=2,)# goodabc=dict(abc=2,cde=5,mama='tata',tata='mama',raz=1,dwa=2,# <- comma here !)

• 2.3dict curly brackets

  # badabc= {'abc':2,'cde':5,'mama':'tata','tata':'mama','raz':1,'dwa':2}# badabc= {'abc':2,'cde':5,'mama':'tata','tata':'mama','raz':1,'dwa':2}# badabc= {'abc':2,'cde':5,'mama':'tata','tata':'mama','raz':1,'dwa':2}# badabc= {'abc':2,'cde':5,'mama':'tata','tata':'mama','raz':1,'dwa':2,}# goodabc= {'abc':2,'cde':5,'mama':'tata','tata':'mama','raz':1,'dwa':2,# <- comma here !}

• 2.4func call and dicts

  abc=abc({'a':1,'b':3,'c':4,# <- comma here !  })abc=abc(dict(a=1,b=2,c=3,# <- comma here !  ))nokaut_api_params=urllib.urlencode({'key':str(nokaut_key),'keyword':str(keyword),'format':'xml','method':'nokaut.Product.getByKeyword','sort_direction':'price_asc','returnType':'full','limit':'1',# <- comma here !  })

• 2.5list comprehension

  # baddata= [model_fieldforform_field,model_fieldinfieldsifform_fieldinform]# baddata= [model_fieldforform_field,model_fieldinfieldsifform_fieldinform  ]# gooddata= [model_fieldforform_field,model_fieldinfieldsifform_fieldinform  ]# good (if exceeding line length limit)data= [model_fieldforform_field,model_fieldinfieldsifform_fieldinform  ]

• 2.6dict comprehension

  # baddata= {model_field:form[form_field].dataforform_field,model_fieldinfieldsifform_fieldinform}# gooddata= {model_field:form[form_field].dataforform_field,model_fieldinfieldsifform_fieldinform  }# good (if exceeding line length limit)data= {model_field:form[form_field].dataforform_field,model_fieldinfieldsifform_fieldinform  }

• 2.7if statement if conditions are too long, store their result in variable with meaningful name

  # badifabcisNoneandbisTrueandc=='mama' \andx!=1orcin ('mama','tata') \orbabcia.age>100:# checks if thing should be done# do something big# badif (abcisNoneandbisTrueandc=='mama'andx!=1orcin ('mama','tata')orbabcia.age>100):# checks if thing should be done# do something big# goodshould_be_done= (# no comment needed !abcisNoneandbisTrueandc=='mama'andx!=1orcin ('mama','tata')orbabcia.age>100)ifshould_be_done:# do something big

• 2.8slashes never use them

  # bad:defx():a_identity=self.aidentityconfirm_set.filter(uuid=self.id_at_provider).first()returna_identity.get_person_who_registed_y().get_full_name()\ifa_identityanda_identity.state=="confirmed"else"A identity is not confirmed yet"# good:defx():a_identity=self.aidentityconfirm_set.filter(uuid=self.id_at_provider).first()ifa_identityanda_identity.state=="confirmed":returna_identity.get_person_who_registed_y().get_full_name()else:return"A identity is not confirmed yet"# there is one exception when you can use slashes, when using chaining methods, examples:# django ORM:posts=Post.objects.filter(blog__id=x)\                    .filter(created_at__gt=y)\                    .filter(desc__contains=z)\                    .order_by('created_at')# Google App Engine NDBgreetings=Greeting.query_book(ancestor_key)\                    .filter(Greeting.userid>=40)\                    .filter(Greeting.userid<100)\                    .fetch(self.GREETINGS_PER_PAGE)# SQLAlchemyfiles=File.query.filter(File.used.is_(False))\                  .filter(File.modified<daysago2)\                  .yield_per(10)# mongoalchemyplace=session.query(Places).filter_by(loc=a)\                             .filter(created_at=b)\                             .descending('created_at').first()

• 2.9Single quotes vs double quotes Use double quotes around strings that are natural language messages and single quotes for small symbol-like strings, for example:

  LIGHT_MESSAGES= {'english':"There are 3 lights.",'pirate':"Arr! Thar be 3 lights."}deflights_message(language,number_of_lights):"""Return a language-appropriate string reporting the light count."""returnLIGHT_MESSAGES[language]defis_pirate(message):"""Return True if the given message sounds piratical."""returnre.search(r"(?i)(arr|avast|yohoho)!",message)isnotNone

  ref:http://stackoverflow.com/a/56190

• 3.1Bail early is idiomatic coding style.

# BAD, really baddefbad_method(a):b=one(a)ifb.isgood():c=two(b)ifc.isok():d=three(c)ifd.hasX():returndelse:raiseNoXErrorelse:raiseNotOKError# GOOD, more clear, more obviousdefgood_method(a):b=one(a)ifnotb.isgood():returnc=two(b)ifnotc.isok()raiseNotOKErrord=three(c)ifnotd.hasX():raiseNoXErrorreturnd