nested class problem

[Stephane Ninin]

Hello all,

I am trying to play with nested class in a script I am making,
and I am not sure I really understand how they work.
Here is some code:

__all__ = ["ITest"]

from exceptions import Exception

class ITest(object):
def __init__(self):
if (self.__class__ == ITest):
raise Exception("ITes t cannot be instanciated")

def read(self,filen ame):
self.__filename = filename

def _getFilename(se lf):
return self.__filename

def make_reader():
return _PTest()
make_reader = staticmethod(ma ke_reader)

class _PTest(ITest):

class _PHandler(objec t):

def __init__(self):
super(_PHandler ,self).__init__ ()
#self.__map={}

def test(self):
pass

def __init__(self):
super(_PTest,se lf).__init__()
def read(self,filen ame):
super(_PTest,se lf).read(filena me)
print "HERE"
print dir()
print dir(self)
print self.__class__
print dir(self.__clas s__)
dh = self._PHandler( )
#dh.test()

if __name__=='__ma in__':

a=ITest.make_re ader()
print dir(a)
b=a.read("")
print b


I want to put class _PHandler in _Ptest,
and use _PHandler in _Ptest methods,
but anything I try doesnot work...

On this configuration, I have:
Traceback (most recent call last):
File "./test.py", line 58, in ?
b=a.read("")
File "./test.py", line 51, in read
dh = self._PHandler( )
File "./test.py", line 34, in __init__
super(_PHandler ,self).__init__ ()
NameError: global name '_PHandler' is not defined

and I have similar problems if I try to access _PHandler
in different ways...
Is this possible somehow ? Or what is the problem with my approach ?
I know I could just dont use nested classes.., but I'd like to try.

Thanks in advance.

Regards,


--
Stephane Ninin

[Peter Otten]

Stephane Ninin wrote:

I am trying to play with nested class in a script I am making,
and I am not sure I really understand how they work.
[..]
class _PTest(ITest):

class _PHandler(objec t):

def __init__(self):
super(_PHandler ,self).__init__ ()
Make that
super(_PTest._P Handler, self).__init__( )

or, even better, omit it entirely. Python class hierarchies tend to remain
flat, because inheritance is only necessary for code reuse, not to indicate
a particular interface.
#self.__map={}

def test(self):
pass

def __init__(self):
super(_PTest,se lf).__init__()
def read(self,filen ame):
super(_PTest,se lf).read(filena me)
print "HERE"
print dir()
print dir(self)
print self.__class__
print dir(self.__clas s__)
dh = self._PHandler( )
#dh.test()

if __name__=='__ma in__':

a=ITest.make_re ader()
print dir(a)
b=a.read("")
print b


I want to put class _PHandler in _Ptest,
and use _PHandler in _Ptest methods,
but anything I try doesnot work...
I think that's you fighting against the language and - a rare case - python
fighting back :-)

On this configuration, I have:
Traceback (most recent call last):
File "./test.py", line 58, in ?
b=a.read("")
File "./test.py", line 51, in read
dh = self._PHandler( )
File "./test.py", line 34, in __init__
super(_PHandler ,self).__init__ ()
NameError: global name '_PHandler' is not defined

and I have similar problems if I try to access _PHandler
in different ways...
Is this possible somehow ? Or what is the problem with my approach ?
I know I could just dont use nested classes.., but I'd like to try.

I fail to see the benefit of nested classes. If you want to bring some
structure into your python application, try packages instead.

Peter