Don't work __getattr__ with __add__
Андрей Симурзин
from A are in the tmpA. So for exapmle:
A + B -- yes , tmpA + B no. I try to call method from A for tmpA. I
can to call simple method, such as change(), bit __add__ - don't
work. If to remove inheritance from object, the code work's. Help me,
please
#--------------------------------------
class A(object):
def __init__( self, x, y ):
self.x = x
self.y = y
pass
#-------
def __add__( self, arg ):
tmp1 = self.x + arg.x
tmp2 = self.y + arg.y
return tmpA( A( tmp1, tmp2 ) )
def change( self, x, y ):
self.x = x
self.y = y
pass
pass
#------------------------------------------
class tmpA( object ):
def __init__( self, theA ):
self.A = theA
pass
#-------
def __call__( self ):
return self.A
#-------
def __coerce__( self, *args ):
return None
#-------
def __getattr__( self, *args ):
name = args[ 0 ]
try:
attr = None
exec "attr = self.__call__().%s" % name
return attr
except :
raise AttributeError
#--------------------------------------
class B( object ):
def __init__( self, x, y):
self.x = x
self.y = y
pass
#-------------------------------------
a=A( 1,2 )
b=B( 3,4 )
tmp_a = a + b #well
tmp_a.change( 0, 0 ) # very well !!!
v = tmp_a + b #TypeError: "unsupported operand type(s) for +: 'tmpA'
and 'B'"
Chris Rebert
> It is object of the class A, in conteiner's class tmpA. Not all method
> from A are in the tmpA. So for exapmle:
> A + B -- yes , tmpA + B no. I try to call method from A for tmpA. I
> can to call simple method, such as change(), bit __add__ - don't
> work. If to remove inheritance from object, the code work's. Help me,
> please
Some clarity has been lost in translation, but I think I get what you're saying.
__add__ and the other double-underscore special methods are not looked
up using __getattr__ or __getattribute__, hence trying to do addition
on tmpA, which does not define an __add__ method, fails.
For a full explanation, read:
http://docs.python.org/reference/datamodel.html#special-method-lookup-for-new-style-classes
Cheers,
Chris
--
http://blog.rebertia.com
Andrey Simurzin
> On Thu, Mar 4, 2010 at 12:25 AM, Андрей Симурзин <asimur...@gmail.com> wrote:
> > It is object of the class A, in conteiner's class tmpA. Not all method
> > from A are in the tmpA. So for exapmle:
> > A + B -- yes , tmpA + B no. I try to call method from A for tmpA. I
> > can to call simple method, such as change(), bit __add__ - don't
> > work. If to remove inheritance from object, the code work's. Help me,
> > please
>
> Some clarity has been lost in translation, but I think I get what you're saying.
> __add__ and the other double-underscore special methods are not looked
> up using __getattr__ or __getattribute__, hence trying to do addition
> on tmpA, which does not define an __add__ method, fails.
>
>
> Cheers,
> Chris
> --http://blog.rebertia.com
Thank you very much