=============
Python Errors
=============


.. code-block:: python

  if true:
  print 1

::

    File "tmp.py", line 2
      print 1
          ^
  IndentationError: expected an indented block



.. code-block:: python

  if true:
      print 1
     print 2

::

    File "tmp.py", line 3
      print 2
            ^
  IndentationError: unindent does not match any outer indentation level



.. code-block:: python

  # -*- encoding: utf-8 -*-
  if true:
  　print 1 # unicode space character

::

    File "tmp.py", line 3
      　print 1 # unicode space character
      ^
  SyntaxError: invalid syntax



.. code-block:: python

  print "こんにちは"

::

    File "tmp.py", line 1
  SyntaxError: Non-ASCII character '\xe3' in file tmp.py on line 1, but no encoding declared; see http://www.python.org/peps/pep-0263.html for details



.. code-block:: python

  # -*- encoding: utf-8 -*-
  print "こんにちは"

::

  こんにちは



.. code-block:: python

  def foo(): pass
  
  foo(1)

::

  Traceback (most recent call last):
    File "tmp.py", line 3, in <module>
      foo(1)
  TypeError: foo() takes no arguments (1 given)



.. code-block:: python

  def foo(x=1): pass
  
  foo(y=1)

::

  Traceback (most recent call last):
    File "tmp.py", line 3, in <module>
      foo(y=1)
  TypeError: foo() got an unexpected keyword argument 'y'



.. code-block:: python

  def foo(x, y, z=0): pass
  
  foo(1, z=1)

::

  Traceback (most recent call last):
    File "tmp.py", line 3, in <module>
      foo(1, z=1)
  TypeError: foo() takes at least 2 arguments (2 given)



.. code-block:: python

  def foo(x=0, **kw):
      print x, kw
  
  foo(1, x=2)

::

  Traceback (most recent call last):
    File "tmp.py", line 4, in <module>
      foo(1, x=2)
  TypeError: foo() got multiple values for keyword argument 'x'



.. code-block:: python

  ''[0]

::

  Traceback (most recent call last):
    File "tmp.py", line 1, in <module>
      ''[0]
  IndexError: string index out of range



.. code-block:: python

  '' + 0

::

  Traceback (most recent call last):
    File "tmp.py", line 1, in <module>
      '' + 0
  TypeError: cannot concatenate 'str' and 'int' objects



.. code-block:: python

  0 + ''

::

  Traceback (most recent call last):
    File "tmp.py", line 1, in <module>
      0 + ''
  TypeError: unsupported operand type(s) for +: 'int' and 'str'



.. code-block:: python

  -''

::

  Traceback (most recent call last):
    File "tmp.py", line 1, in <module>
      -''
  TypeError: bad operand type for unary -: 'str'



.. code-block:: python

  x

::

  Traceback (most recent call last):
    File "tmp.py", line 1, in <module>
      x
  NameError: name 'x' is not defined



.. code-block:: python

  u'' + '\xFF'

::

  Traceback (most recent call last):
    File "tmp.py", line 1, in <module>
      u'' + '\xFF'
  UnicodeDecodeError: 'ascii' codec can't decode byte 0xff in position 0: ordinal not in range(128)



.. code-block:: python

  {}['x']

::

  Traceback (most recent call last):
    File "tmp.py", line 1, in <module>
      {}['x']
  KeyError: 'x'



.. code-block:: python

  [].x

::

  Traceback (most recent call last):
    File "tmp.py", line 1, in <module>
      [].x
  AttributeError: 'list' object has no attribute 'x'



.. code-block:: python

  import x

::

  Traceback (most recent call last):
    File "tmp.py", line 1, in <module>
      import x
  ImportError: No module named x



.. code-block:: python

  int("a")

::

  Traceback (most recent call last):
    File "tmp.py", line 1, in <module>
      int("a")
  ValueError: invalid literal for int() with base 10: 'a'



.. code-block:: python

  "%s %s %s" % (1, 2)

::

  Traceback (most recent call last):
    File "tmp.py", line 1, in <module>
      "%s %s %s" % (1, 2)
  TypeError: not enough arguments for format string



.. code-block:: python

  "%s %s" % [1, 2]

::

  Traceback (most recent call last):
    File "tmp.py", line 1, in <module>
      "%s %s" % [1, 2]
  TypeError: not enough arguments for format string



.. code-block:: python

  1 / 0

::

  Traceback (most recent call last):
    File "tmp.py", line 1, in <module>
      1 / 0
  ZeroDivisionError: integer division or modulo by zero



.. code-block:: python

  def foo():
      return
  
  foo() + 1

::

  Traceback (most recent call last):
    File "tmp.py", line 4, in <module>
      foo() + 1
  TypeError: unsupported operand type(s) for +: 'NoneType' and 'int'



.. code-block:: python

  class Foo(object):
      def say(self):
          pass
  
  Foo.say()

::

  Traceback (most recent call last):
    File "tmp.py", line 5, in <module>
      Foo.say()
  TypeError: unbound method say() must be called with Foo instance as first argument (got nothing instead)



.. code-block:: python

  class A(object): pass
  class B(object): pass
  class AB(A, B): pass
  class BA(B, A): pass
  class C(AB, BA): pass

::

  Traceback (most recent call last):
    File "tmp.py", line 5, in <module>
      class C(AB, BA): pass
  TypeError: Error when calling the metaclass bases
      Cannot create a consistent method resolution
  order (MRO) for bases B, A



.. code-block:: python

  def func(a=[]):
      a.append(1)
      return a
  
  print func()
  print func()
  print func()

::

  [1]
  [1, 1]
  [1, 1, 1]



.. code-block:: python

  def f():
      print "called"
  
  def func(x=f()):
      pass

::

  called



.. code-block:: python

  # assignment in bar doesn't affect outside
  def foo():
      x = 0
      def bar():
          x = 1
  
      bar()
      print x
  
  foo()

::

  0



.. code-block:: python

  # list comprehension doesn't make scope
  funcs = [(lambda: x) for x in range(3)]
  print funcs[0]()
  print funcs[1]()

::

  2
  2



.. code-block:: python

  x = 0
  def foo():
      x += 1
  
  foo()

::

  Traceback (most recent call last):
    File "tmp.py", line 5, in <module>
      foo()
    File "tmp.py", line 3, in foo
      x += 1
  UnboundLocalError: local variable 'x' referenced before assignment



.. code-block:: python

  x = 0
  def foo():
      global x
      x += 1
  
  foo()
  print x

::

  1



.. code-block:: python

  # class variable is not a global variable
  class Foo(object):
      x = 1
      def foo(self):
          print x
  
  Foo().foo()

::

  Traceback (most recent call last):
    File "tmp.py", line 7, in <module>
      Foo().foo()
    File "tmp.py", line 5, in foo
      print x
  NameError: global name 'x' is not defined



.. code-block:: python

  class Foo(object):
      x = 1
      def foo(self):
          print self.x
  
  Foo().foo()

::

  1



.. code-block:: python

  # class variable is shared by instances
  class Foo(object):
      x = []
      def foo(self):
          self.x.append(1)
          print self.x
  
  Foo().foo()
  Foo().foo()

::

  [1]
  [1, 1]



.. code-block:: python

  def foo(a=1, b): pass

::

    File "tmp.py", line 1
      def foo(a=1, b): pass
  SyntaxError: non-default argument follows default argument



.. code-block:: python

  def foo(a=1, b): pass

::

    File "tmp.py", line 1
      def foo(a=1, b): pass
  SyntaxError: non-default argument follows default argument



.. code-block:: python

  object.a = 1

::

  Traceback (most recent call last):
    File "tmp.py", line 1, in <module>
      object.a = 1
  TypeError: can't set attributes of built-in/extension type 'object'



.. code-block:: python

  class MetaFoo(type): pass
  class MetaBar(type): pass
  class Foo(object):
      __metaclass__ = MetaFoo
  
  class Bar(Foo):
      __metaclass__ = MetaBar

::

  Traceback (most recent call last):
    File "tmp.py", line 6, in <module>
      class Bar(Foo):
  TypeError: Error when calling the metaclass bases
      metaclass conflict: the metaclass of a derived class must be a (non-strict) subclass of the metaclasses of all its bases



.. code-block:: python

  class Foo(object):
      @property
      def foo(self):
          return self.foo
  
  f = Foo()
  f.foo = 1

::

  Traceback (most recent call last):
    File "tmp.py", line 7, in <module>
      f.foo = 1
  AttributeError: can't set attribute



.. code-block:: python

  while 1:
   while 1:
    while 1:
     while 1:
      while 1:
       while 1:
        while 1:
         while 1:
          while 1:
           while 1:
            while 1:
             while 1:
              while 1:
               while 1:
                while 1:
                 while 1:
                  while 1:
                   while 1:
                    while 1:
                     while 1:
                      while 1:
                       print "hello"

::

  SystemError: too many statically nested blocks



.. code-block:: python

  return

::

    File "tmp.py", line 1
      return
  SyntaxError: 'return' outside function