extend getattr()

[Rotlaus]

Hello,

lets assume i have some classes:

class A(object):
def __init__(self):
b = B()

class B(object):
def __init__(self):
c = C()

class C(object):
def __init__(self):
pass

and now i wanna do something like this:

a=A()
c=getattr(a, 'b.c')

I know this doesn't work, but what can i do to get this or a similar
functionality to get it work for this sample and for even more nested
classes?

Kind regards,

Andre

 

[Gerhard Häring]

Hello,

lets assume i have some classes:
[...]

a=A()
c=getattr(a, 'b.c')

I know this doesn't work, but what can i do to get this or a similar
functionality to get it work for this sample and for even more nested
classes?

Just recursively apply the getattr(), like this:

class A(object):
def __init__(self):
self.b = B()

class B(object):
def __init__(self):
self.c = C()

class C(object):
def __init__(self):
pass

def ext_getattr(obj, attr):
for subattr in attr.split("."):
obj = getattr(obj, subattr)
return obj

a=A()
c = ext_getattr(a, 'b.c')

-- Gerhard

 

[Cédric Lucantis]

Le Thursday 26 June 2008 13:06:53 Rotlaus, vous avez écrit :

Hello,

lets assume i have some classes:

class A(object):
def __init__(self):
b = B()

class B(object):
def __init__(self):
c = C()

note you're just defining some local variables here, should be self.b = B()
and self.c = C().

class C(object):
def __init__(self):
pass

and now i wanna do something like this:

a=A()
c=getattr(a, 'b.c')

I know this doesn't work, but what can i do to get this or a similar
functionality to get it work for this sample and for even more nested
classes?

You could do it manually:

c = getattr(getattr(a, 'b'), 'c')

or make it automatic:

def get_dotted_attr (obj, dotted_attr) :
for attr in dotted_attr.split('.') :
obj = getattr(obj, attr)
return obj

a = A()
print 'a.b.c = %s' % get_dotted_attr(a, 'b.c')

 

[George Sakkis]

Le Thursday 26 June 2008 13:06:53 Rotlaus, vous avez écrit :





note you're just defining some local variables here, should be self.b = B()
and self.c = C().





You could do it manually:

c = getattr(getattr(a, 'b'), 'c')

or make it automatic:

def get_dotted_attr (obj, dotted_attr) :
for attr in dotted_attr.split('.') :
obj = getattr(obj, attr)
return obj

a = A()
print 'a.b.c = %s' % get_dotted_attr(a, 'b.c')

FYI, this feature will exist in operator.attrgetter from Python 2.6,
i.e. you'll be able to say attrgetter('b.c')(a).

George