global destructor not called?

[Neal Becker]

To implement logging, I'm using a class:
class logger (object):
def __init__ (self, name):
self.name = name
self.f = open (self.name, 'w')
def write (self, stuff):
self.f.write (stuff)
def close (self):
self.f.close()
def flush (self):
self.f.flush()
def reopen (self):
self.f.flush()
self.f.close()
os.rename (self.name, self.name + '.old')
self.f = open (self.name, 'w')
def __del__ (self):
try:
os.remove (self.name + '.old')
except:
pass

And setting:
sys.stderr = logger(...)

It seems my cleanup (__del__) is never called, even though I believe my
program exits normally. What's wrong?

[Bruno Desthuilliers]

Neal Becker a écrit :

To implement logging, I'm using a class:

If I may ask : any reason not to use the logging module in the stdlib ?

class logger (object):
def __init__ (self, name):
self.name = name
self.f = open (self.name, 'w')
def write (self, stuff):
self.f.write (stuff)
def close (self):
self.f.close()
def flush (self):
self.f.flush()
def reopen (self):
self.f.flush()
self.f.close()
os.rename (self.name, self.name + '.old')
self.f = open (self.name, 'w')
def __del__ (self):
try:
os.remove (self.name + '.old')
except:
pass

And setting:
sys.stderr = logger(...)

It seems my cleanup (__del__) is never called,

What makes you think so ?

even though I believe my
program exits normally. What's wrong?

Not enough data...

[Neal Becker]

Bruno Desthuilliers wrote:

Neal Becker a écrit :

>To implement logging, I'm using a class:

If I may ask : any reason not to use the logging module in the stdlib ?

Don't exactly recall, but needed some specific behavior and it was just
easier this way.

>

>class logger (object):
def __init__ (self, name):
self.name = name
self.f = open (self.name, 'w')
def write (self, stuff):
self.f.write (stuff)
def close (self):
self.f.close()
def flush (self):
self.f.flush()
def reopen (self):
self.f.flush()
self.f.close()
os.rename (self.name, self.name + '.old')
self.f = open (self.name, 'w')
def __del__ (self):
try:
os.remove (self.name + '.old')
except:
pass

And setting:
sys.stderr = logger(...)

It seems my cleanup (__del__) is never called,

What makes you think so ?

Cleanup should remove file file '.old', and it wasn't removed. Adding
atexit.register (self.__del__) to the logger constructor DID fix it.

>

>even though I believe my
program exits normally. What's wrong?

Not enough data...

[bruno.desthuilliers]

On Jun 15, 7:07 pm, Neal Becker <[e-mail]:

Bruno Desthuilliers wrote:

Neal Becker a écrit :

To implement logging, I'm using a class:

If I may ask : any reason not to use the logging module in the stdlib ?

Don't exactly recall, but needed some specific behavior and it was just
easier this way.

Ok, that's was just in case you didn't know about this module...

>

class logger (object):
def __init__ (self, name):
self.name = name
self.f = open (self.name, 'w')
def write (self, stuff):
self.f.write (stuff)
def close (self):
self.f.close()
def flush (self):
self.f.flush()
def reopen (self):
self.f.flush()
self.f.close()
os.rename (self.name, self.name + '.old')
self.f = open (self.name, 'w')
def __del__ (self):
try:
os.remove (self.name + '.old')
except:
pass

And setting:
sys.stderr = logger(...)

It seems my cleanup (__del__) is never called,

What makes you think so ?

Cleanup should remove file file '.old',
and it wasn't removed.
Adding
atexit.register (self.__del__) to the logger constructor DID fix it.

Mmm... If I read the language's references, I see this:

"""
It is not guaranteed that __del__() methods are called for objects
that still exist when the interpreter exits.
"""
http://docs.python.org/ref/customization.html

Hopefully you fuond the right way to ensure correct clean-up !-)

(damn, I knew I rembered something special about destructors... but I
couldn't remember exactly what.)

[Duncan Booth]

"br*****************@gmail.com" <br*****************@gmail.comwrote:

> def __del__ (self):
try:
os.remove (self.name + '.old')
except:
pass

>And setting:
sys.stderr = logger(...)

>It seems my cleanup (__del__) is never called,

....

>
Mmm... If I read the language's references, I see this:

"""
It is not guaranteed that __del__() methods are called for objects
that still exist when the interpreter exits.
"""
http://docs.python.org/ref/customization.html

Hopefully you fuond the right way to ensure correct clean-up !-)

(damn, I knew I rembered something special about destructors... but I
couldn't remember exactly what.)

I don't think you can tell from this description whether the __del__ method
was called or not.

Even if sys.stderr is destroyed before Python exits and the __del__ method
is called the OP will still get the effect described: the global variables
in the module defining logger will have been cleared before stderr is
destroyed, so __del__ will simply throw an NameError when trying to access
os.