From 19cda4a8b946ef2265fb182e1e672b2df5adcd44 Mon Sep 17 00:00:00 2001 From: Julio Biason Date: Mon, 27 Jun 2016 16:39:41 -0300 Subject: [PATCH] added info about the elses --- python.html | 579 ++++++++++++++++++++++++++++++++++------------------ 1 file changed, 375 insertions(+), 204 deletions(-) diff --git a/python.html b/python.html index 6a0572a..b24da0f 100644 --- a/python.html +++ b/python.html @@ -352,7 +352,7 @@ python meuscript.py >>> a = 'Python' >>> b = "Python" >>> c = """Python ->>> Rocks!""" +... Rocks!"""

@@ -377,7 +377,7 @@ python meuscript.py 


 >>> a = {'Python': 'Rocks',
->>>      1: 1.0}
+...      1: 1.0}

@@ -411,7 +411,7 @@ set(['a']) @@ -434,7 +434,7 @@ set(['a']) 


 >>> if a == 1:
->>>     b = 2
+...     b = 2
 >>> c = 3

@@ -445,9 +445,9 @@ set(['a']) 


 >>> a = 1
 >>> while True:
->>>     a += 1
->>>     if a > 10:
->>>         break
+...     a += 1
+...     if a > 10:
+...         break

@@ -514,7 +514,7 @@ True 


 >>> soma = 0
 >>> for valor em [345, 123, 123, 34]:
->>>     soma += valor
+...     soma += valor

@@ -545,7 +545,7 @@ True 


 >>> for l in 'Python':
->>>     print l
+...     print l

@@ -555,7 +555,7 @@ True 


 >>> d =  {'Python': 'Rocks', 'Parrot': 'Dead', 'Favorite Color': 'Blue'}
 >>> for key in d:
->>>    print key, d[key]
+...    print key, d[key]

@@ -565,7 +565,7 @@ True 


 >>> d =  {'Python': 'Rocks', 'Parrot': 'Dead', 'Favorite Color': 'Blue'}
 >>> for (key, value) in d.iteritems():
->>>     print key, value
+...     print key, value

Forma considerada "correta" é a anterior.

@@ -595,7 +595,7 @@ iterável[start:end:step] 


 >>> a = [1, 2, 3, 4]
->>> print a[1:2]
+... print a[1:2]
 [2]

@@ -611,7 +611,7 @@ iterável[start:end:step] 


 >>> a = [1, 2, 3, 4]
->>> print a[:2]
+... print a[:2]
 [1, 2]

@@ -621,7 +621,7 @@ iterável[start:end:step] 


 >>> a = [1, 2, 3, 4]
->>> print a[1:-1]
+... print a[1:-1]
 [2, 3]

@@ -631,7 +631,7 @@ iterável[start:end:step] 


 >>> a = 'Python Rocks'
->>> print a[7:-1]
+... print a[7:-1]
 'Rock'

@@ -640,7 +640,7 @@ iterável[start:end:step]

Deixar os dois índices em branco cria uma cópia "flat".


 >>> a = [1, 2, 3, 4]
->>> print a[:]
+... print a[:]
 [1, 2, 3, 4]

@@ -672,7 +672,7 @@ iterável[start:end:step] 


 >>> def funcao(a, b, c):
->>>     return (a + b) / c
+...     return (a + b) / c

@@ -681,7 +681,7 @@ iterável[start:end:step] 


 >>> def funcao(a, b, c):
->>>     return (a + b) / c
+...     return (a + b) / c
 >>>
 >>> funcao(b=2, c=3, a=10)
 4
@@ -734,6 +734,8 @@ iterável[start:end:step]
 
                         
Não existe função para o destrutor.

 
+                        
(Existe, mas ninguém usa.)

+
                         
Existem ainda outras funções
                             mágicas, mas não vamos falar sobre elas
                             nesse momento.
 
@@ -741,10 +743,10 @@ iterável[start:end:step]
                     

                         

 >>> class MyClasse(object):
->>>     def __init__(self):
->>>         self.valor = 0
->>>     def show(self):
->>>         print self.valor
+...     def __init__(self):
+...         self.valor = 0
+...     def show(self):
+...         print self.valor
                         

                     

 
@@ -766,10 +768,10 @@ iterável[start:end:step]
 
                         

 >>> class MyClasse(object):
->>>     def __init__(self, name):
->>>         self.name = name
->>>     def show(self):
->>>         print self.name
+...     def __init__(self, name):
+...         self.name = name
+...     def show(self):
+...         print self.name
 
 >>> my = MyClasse('Julio')
 >>> my.show()
@@ -777,17 +779,34 @@ Julio
                         

                     
 
+                    

+                        
Propriedades podem ser injetadas a qualquer momento.

+
+                        

+>>> class A(object):
+...     def __init__(self):
+...         self.value = 10
+>>>
+>>> a = A()
+>>> a.name = 'Julio'
+                        

+
+                        
Inserção de propriedades pode ser
+                            barrada com o uso da variável mágica
+                            __slots__, mas raramente é usado.

+                    

+
                     

                         
Herança

 
                         

 >>> class A(object):
->>>     def __init__(self):
->>>         self.value = 10
+...     def __init__(self):
+...         self.value = 10
 >>> class B(A):
->>>     def __init__(self):
->>>         super(B, self).__init__()
->>>         self.name = 'AAAA'
+...     def __init__(self):
+...         super(B, self).__init__()
+...         self.name = 'AAAA'
                         

                     

 
@@ -796,14 +815,14 @@ Julio
 
                         

 >>> class A(object):
->>>     def __init__(self):
->>>         self.value = 10
+...     def __init__(self):
+...         self.value = 10
 >>> class B(object):
->>>     def __init__(self):
->>>         self.name = 'AAAA'
+...     def __init__(self):
+...         self.name = 'AAAA'
 >>> class C(A, B):
->>>     def __init__(self):
->>>         super(C, self).__init__()
+...     def __init__(self):
+...         super(C, self).__init__()
                         

                     
 
@@ -812,17 +831,124 @@ Julio
                     
 
                     

-                        
Propriedades podem ser injetadas a qualquer momento.

+                        
super() é mais usado para resolução
+                            hierárquia com herança múltipla.

+                    

 
+                    

                         

->>> class A(object):
->>>     def __init__(self):
->>>         self.value = 10
->>>
->>> a = A()
->>> a.name = 'Julio'
+>>> class Adao(object): pass
+>>> class Eva(object): pass
+>>> class AvoPaterno(Adao, Eva): pass
+>>> class AvohPaterna(Adao, Eva): pass
+>>> class AvoMaterno(Adao, Eva): pass
+>>> class AvohMaterna(Adao, Eva): pass
+>>> class Pai(AvoPaterno, AvohPaterna): pass
+>>> class Mae(AvoMaterno, AvohMaterna): pass
+>>> class Filho(Pai, Mae): pass
+                        

+
+                        

+>>> help(Filho)
+                        

+                    

+
+                    

+                        

+Help on class Filho in module __main__:
+
+class Filho(Pai, Mae)
+ |  Method resolution order:
+ |      Filho
+ |      Pai
+ |      AvoPaterno
+ |      AvohPaterna
+ |      Mae
+ |      AvoMaterno
+ |      AvohMaterna
+ |      Adao
+ |      Eva
+ |      __builtin__.object
+                        

+                    

+
+                    

+                        
A ordem de resolução pode ser usada para inserir
+                            mocks sem o uso de mocks.

+
+                        
... embora só sirva para mockar
+                            objetos "é um" e não "contém um".

+                    

+
+                    

+                        

+>>> class Robo(object):
+...    def pegar(self, ferramenta):
+...        print 'Pegando', ferramenta
+...    def pra_frente(self):
+...        print 'Movendo pra frente'
+...    def pra_tras(self):
+...        print 'Voltando'
+...    def largar(self):
+...        print 'Largando ferramenta'
+                        

+                    

+
+                    

+                        

+>>> class RoboDeLimpeza(Robo):
+...    def clean(self, repeticoes=10):
+...        super(Robo, self).pegar('vassoura')
+...        for _ in xrange(repeticoes):
+...            super(Robo, self).pra_frente()
+...            super(Robo, self).pra_tras()
+...        super(Robo, self).largar()
+                        

+                    

+
+                    

+                        

+>>> class MockRobo(Robo):
+...     def __init__(self):
+...         self.acoes = []
+...     def pegar(self, ferramenta):
+...         self.acoes.append('Pegar {}'.format(ferramenta))
+...     def pra_frente(self):
+...         self.acoes.append('frente')
+...     def pra_tras(self):
+...         self.acoes.append('tras')
+...     def largar(self):
+...         self.acoes.append('largar')
+                        

+                    

+
+                    

+                        

+>>> class MockRoboDeLimpeza(RoboDeLimpeza, MockRobo):
+...     pass
+                        

+                    

+
+                    

+                        

+Help on class MockRoboDeLimpeza in module __main__:
+
+class MockRoboDeLimpeza(RoboDeLimpeza, MockRobo)
+ |  Method resolution order:
+ |      MockRoboDeLimpeza
+ |      RoboDeLimpeza
+ |      MockRobo
+ |      Robo
+ |      __builtin__.object
                         

                     

+
+                    

+                        

+                            Mais informações no vídeo de Raymond Hettinger:
+                            Super Considered super!
+                        

+                    

                 
 
                 

@@ -867,9 +993,8 @@ Julio
                     

                         

 >>> def a(l=[]):
->>>     l.append(1)
->>>     print l
->>>
+...     l.append(1)
+...     print l
 >>> a()
 [1]
 >>> a()
@@ -882,10 +1007,9 @@ Julio
 
                         

 >>> def a(l=None):
->>>     if not l:
->>>         l = []
->>>     l.append(1)
->>>
+...     if not l:
+...         l = []
+...     l.append(1)
 >>> a()
 [1]
 >>> a()
@@ -906,8 +1030,7 @@ Julio
                     

                         

 >>> def a(*args):
->>>     print args
->>>
+...     print args
 >>> a(1)
 [1]
 >>> a(1, 2, 3, 4, 5)
@@ -920,8 +1043,7 @@ Julio
                     

                         

 >>> def a(**kwargs):
->>>     print kwargs
->>>
+...     print kwargs
 >>> a(a=1)
 {'a': 1}
 >>> a(value1=10, a=2)
@@ -934,9 +1056,8 @@ Julio
                     

                         

 >>> def a(*args, **kwargs):
->>>     print args
->>>     print kwargs
->>>
+...     print args
+...     print kwargs
 >>> a(a=1)
 []
 {'a': 1}
@@ -949,17 +1070,72 @@ Julio
                     

                         

 >>> def a(a, b, *args, name=None, **kwargs):
->>>     print 'a =', a
->>>     print 'b =', b
->>>     print 'args =', args
->>>     print 'name = ', name
->>>     print 'kwargs =', kwargs
+...     print 'a =', a
+...     print 'b =', b
+...     print 'args =', args
+...     print 'name = ', name
+...     print 'kwargs =', kwargs
                         

 
                         
Saída de uma chamada desta função fica a cargo do leitor.

                     

                 

 
+                

+                    

+                        
for tem else

+                    

+
+                    

+                        

+>>> for i in xrange(10):
+...     if i == 1:
+...         break
+... else:
+...     print 'Oh no'
+                        

+
+                        
WAT

+                    

+
+                    

+                        
for tem else

+
+                        
else é chamado se a execução do loop
+                            chegar ao final.

+
+                        

+>>> for record in all_content:
+...     if record.name = search:
+...         found = record
+...         break
+... else:
+...     found = None
+                        

+                    

+                

+
+                

+                    

+                        
try tem else

+                    

+
+                    

+                        

+>>> try:
+...    func_that_raises_exception()
+... else:
+...     print 'Yay!'
+                        

+
+                        
else é chamado quando
+                            exceções não ocorrerem.

+
+                        
finally
+                            SEMPRE é chamado.

+                    

+                

+
                 

                     

                         
"Functions are First Class Citizens"

@@ -968,12 +1144,10 @@ Julio
                     

                         

 >>> def funcao(a, b, c):
->>>     return (a + b) / c
->>>
+...     return (a + b) / c
 >>> def check(a, b, c, condition, function):
->>>     if condition:
->>>         print function(a, b, c)
->>>
+...     if condition:
+...         print function(a, b, c)
 >>> check(1, 2, 3, True, funcao)
 1
 >>> check(1, 2, 3, False, funcao)
@@ -988,12 +1162,10 @@ Julio
 
                         

 >>> class A(object):
->>>     def __init__(self):
->>>         self.value = 10
->>>
->>> def show_name(self):
->>>     print 'Julio'
->>>
+...     def __init__(self):
+...         self.value = 10
+... def show_name(self):
+...     print 'Julio'
 >>> a = A()
 >>> a.show = show_name
 >>> a.show()
@@ -1017,7 +1189,7 @@ Julio
                     

                         

 >>> def retrieve(connection):
->>>     # faz algo com a conexão para recuperar dados.
+...     # faz algo com a conexão para recuperar dados.
                         

 
                         
Problema: antes de sair executando algo na conexão, tem que ser
@@ -1030,15 +1202,15 @@ Julio
 
                         

 >>> def retrieve(connection):
->>>     # faz algo com a conexão para recuperar dados.
->>>
+...     # faz algo com a conexão para recuperar dados.
+
 >>> def update(connection):
->>>     # atualiza algo usando a função
->>>
+...     # atualiza algo usando a função
+
 >>> def check(connection, call):
->>>     if not connection.is_connected:
->>>         connection.retry()
->>>     call(connection)
+...     if not connection.is_connected:
+...         connection.retry()
+...     call(connection)
                         

 
                         
Novo problema: Todo lugar onde antes era chamado retrieve
@@ -1052,18 +1224,17 @@ Julio
 
                         

 >>> from functools import wrap
->>>
 >>> def check(func):
->>>     def check_conn(*args, **kwargs):
->>>         # acha a conexão em args ou kwargs
->>>         if not connection.is_connected:
->>>             connection.retry()
->>>         return func(*args, **kwargs)
->>>     return check_conn
->>>
+...     def check_conn(*args, **kwargs):
+...         # acha a conexão em args ou kwargs
+...         if not connection.is_connected:
+...             connection.retry()
+...         return func(*args, **kwargs)
+...     return check_conn
+
 >>> @check
 >>> def retrieve(connection):
->>>     # faz algo com a conexão para recuperar dados
+...     # faz algo com a conexão para recuperar dados
                         

 
                         
Não precisa alterar nenhuma chamada de retrieve.

@@ -1078,22 +1249,22 @@ Julio
 
                         

 >>> class CheckConn(object):
->>>    def __init__(self, func):
->>>        self.func = func
->>>
->>>     def __call__(self, *args, **kwargs):
->>>         if 'connection' in kwargs:
->>>             connection = kwargs['connection']
->>>         else:
->>>             connection = args[0]
->>>
->>>         if not connection.is_connected:
->>>             connection.retry()
->>>         self.func(*args, **kwargs)
+...    def __init__(self, func):
+...        self.func = func
+...
+...     def __call__(self, *args, **kwargs):
+...         if 'connection' in kwargs:
+...             connection = kwargs['connection']
+...         else:
+...             connection = args[0]
+...
+...         if not connection.is_connected:
+...             connection.retry()
+...         self.func(*args, **kwargs)
 
 >>> @CheckCon
 >>> def retrieve(connection):
->>>     # retrieve
+...     # retrieve
                         

                     

 
@@ -1111,16 +1282,16 @@ Julio
 
                         

 >>> class CheckConn(object):
->>>    def __init__(self, func):
->>>        self._func = func
->>>
->>>    @property
->>>    def func(self):
->>>        return self._func
->>>
->>>    @func.setter
->>>    def func(self, value):
->>>        self._func = func
+...    def __init__(self, func):
+...        self._func = func
+...
+...    @property
+...    def func(self):
+...        return self._func
+...
+...    @func.setter
+...    def func(self, value):
+...        self._func = func
                         

                     

 
@@ -1129,112 +1300,112 @@ Julio
 
                         

 >>> class CheckConn(object):
->>>    def __init__(self, func):
->>>        self._func = func
->>>
->>>    @staticmethod
->>>    def from_text(self, text):
->>>        return CheckConn(getattr(self, text))
+...    def __init__(self, func):
+...        self._func = func
+...
+...    @staticmethod
+...    def from_text(self, text):
+...        return CheckConn(getattr(self, text))
                         

                     

                 

 
-				

-					

-						
Comprehensions e Generators

+                

+                    

+                        
Comprehensions e Generators

 
-						
Python permite criar listas processando listas sem
-							for com list
-								comprehensions.

+                        
Python permite criar listas processando listas sem
+                            for com list
+                                comprehensions.

 
-						

+                        

 >>> a = [1, 2, 3]
 >>> [item * 2 for item in a]
 >>> [2, 4, 6]
-						

+                        

 
-						
Pra quem gosta de coisas "funcionais", é o mesmo que
-							map.

+                        
Pra quem gosta de coisas "funcionais", é o mesmo que
+                            map.

 
-						

+                        

 >>> a = [1, 2, 3]
 >>> map(lamba f: f * 2, a)
 >>> [2, 4, 6]
-						

-					

+                        

+                    

 
-					

-						
Comprehensions (contd.)

-						
É possível filtrar elementos com list comprehensions.

+                    

+                        
Comprehensions (contd.)

+                        
É possível filtrar elementos com list comprehensions.

 
-						

+                        

 >>> a = [1, 2, 3]
 >>> [item for item in a if item > 2]
 >>> [3]
-						

+                        

 
-						
Funcionalmente, é o mesmo que filter.

+                        
Funcionalmente, é o mesmo que filter.

 
-						

+                        

 >>> a = [1, 2, 3]
 >>> filter(lambda f: f > 2, a)
 >>> [3]
-						

-					

+
+ -
-

Generators

+
+

Generators

-

Enquanto que comprehensions criam novas listas, generators - geram elementos sob demanda.

+

Enquanto que comprehensions criam novas listas, generators + geram elementos sob demanda.

- 

+                        

 >>> a = [1, 2, 3]
 >>> (item * 2 for item in a)
 <generator object <genexpr> at 0x7f8673dfc050>
-						

-
+ +
-
-
Generators (contd.)
+
+
Generators (contd.)
- 

+                        

 >>> [item for item in range(5000000)]
-						

+
-

vs

+

vs

- 

+                        

 >>> (item for item in xrange(5000000))
-						

-
+ +
-
-
Generators (contd.)
+
+
Generators (contd.)
- 

+                        

 >>> [item for item in range(5000000)][:5]
-						

+
-

vs

+

vs

- 

+                        

 >>> (item for item in xrange(5000000))[:5]
-						

-
+ +
-
-
Generators (contd.)
+
+
Generators (contd.)
- 

+                        

 >>> def gen(max_value):
->>> 	for value in xrange(max_value):
->>> 		yield value * 2
-						

+...    for value in xrange(max_value):
+...        yield value * 2
+
-

Generator functions não podem ter return!

-
-
+

Generator functions não podem ter return!

+ +
@@ -1249,45 +1420,45 @@ Julio

Context Managers

- 

+                        

 >>> class Connection(object):
->>>    def __init__(self):
->>>        self._conn = None
->>>
->>>    def __enter__(self):
->>>        self._conn = self._make_connection()
->>>        return self._conn
->>>
->>>    def __exit__(self, exc_type, exc_value, traceback):
->>>        self._conn.close()
->>>        if exc_type:    # then exc_value and traceback
->>>            print "Exception!", exc_type, exc_value
->>>            print traceback
-						

-
-						

+...    def __init__(self):
+...        self._conn = None
+...
+...    def __enter__(self):
+...        self._conn = self._make_connection()
+...        return self._conn
+...
+...    def __exit__(self, exc_type, exc_value, traceback):
+...        self._conn.close()
+...        if exc_type:    # then exc_value and traceback
+...            print "Exception!", exc_type, exc_value
+...            print traceback
+                        

+
+                        

 >>> with Connection() as connection:
->>>     connection.request('Value')
-						

+...     connection.request('Value')
+

Context Managers vs Exceptions

- 

+                        

 >>> try:
->>>     conn = self._make_connection()
->>>     conn.request('value')
->>> finally:
->>>     conn.close()
->>> except Exception as exc:  # Bare exceptions are BAAAADDD!
->>>     print 'Exception!', exc
-						

+...     conn = self._make_connection()
+...     conn.request('value')
+... finally:
+...     conn.close()
+... except Exception as exc:  # Bare exceptions are BAAAADDD!
+...     print 'Exception!', exc
+
-
+

Docstrings

@@ -1296,8 +1467,8 @@ Julio 

 >>> def func(a):
->>>     """Função mágica"""
->>>     return a
+...     """Função mágica"""
+...     return a
 
 >>> print func.__doc__
 Função mágica
@@ -1388,7 +1559,7 @@ def send(sender, recipient, message_body, priority):
                             diretórios a serem pesquisados e um makefile com a opção
                             html para geração de arquivos HTML.)
-
+