Dave Angel wrote:
> But I'm guessing you want something that automatically deletes objects
> whenever the last reference disappears. That's an implementation
> detail, not a language guarantee. In particular CPython does what you
> want, by using reference counting. That's the only Python I've used, so
> it's only hearsay when I say that other implementations, (maybe Cython
> or Jython) do not all work the same way.
Here are some examples from Kubuntu 9.04's zoo of python implementations:
$ cat del.py
import sys
print sys.version
class A(object):
def __init__(self, x):
self.x = x
def __del__(self):
print "releasing A(%r)" % self.x
def f():
a = A("local in function")
f()
a = A("global (one ref)")
c = A("global (cycle)")
c.a = c
del c
b = A("global (no refs)")
del b
print "about to quit"
$ python del.py
2.6.2 (release26-maint, Apr 19 2009, 01:58:18)
[GCC 4.3.3]
releasing A('local in function')
releasing A('global (no refs)')
about to quit
releasing A('global (one ref)')
$ jython del.py
2.2.1
about to quit
$ ipy del.py
2.4.0 (IronPython 1.1.1 (1.1.1) on .NET 2.0.50727.42)
about to quit
releasing A('global (no refs)')
releasing A('global (cycle)')
releasing A('local in function')
Unhandled Exception: System.ArgumentException: I/O operation on closed file
at IronPython.Runtime.PythonFile.ThrowIfClosed () [0x00000]
at IronPython.Runtime.PythonFile.Write (System.String s) [0x00000]
$
IronPython sometimes segfaulted.
Peter
--
http://mail.python.org/mailman/listinfo/python-list
