How does Mr. Martelli's Borg recipe work ?
bokr at oz.net
Wed Jul 23 23:05:50 CEST 2003
On Wed, 23 Jul 2003 12:48:00 -0600, Steven Taschuk <staschuk at telusplanet.net> wrote:
>Quoth John Roth:
>> I can kind of understand the justification for the Borg pattern
>> in Python releases before 2.2, because there was no way of
>> creating a true singleton in those releases. However, in 2.2 and
>> later, it's really easy to create one using new style classes.
> [...implementing singletons with __new__...]
>> That being the case, I'd like to see the Borg pattern go the way
>> of a fondly remembered hack that is no longer necessary.
>Just out of curiosity: why do you prefer singletons to Borgs in
>the first place?
>(I don't see Borg as a hack to get the behaviour of a singleton; I
>see it as a more direct way to solve the problem which singletons
>are supposed to solve. Thus to me Borg is actually preferable, in
>those exceedingly rare cases when that problem actually arises.)
How about just
import zerolengthfile as borginstancename
and using it? E.g.,
[14:04] C:\pywk\clp>dir zer*, a.* b.*
03-07-23 13:50 0 zero_len.py
03-07-23 14:01 28 a.py
03-07-23 14:02 28 b.py
[14:05] C:\pywk\clp>type a.py
import zero_len as aborg
[14:05] C:\pywk\clp>type b.py
import zero_len as bborg
Python 2.2.2 (#37, Oct 14 2002, 17:02:34) [MSC 32 bit (Intel)] on win32
Type "help", "copyright", "credits" or "license" for more information.
>>> import zero_len as inter
>>> import a
>>> import b
['__builtins__', '__doc__', '__name__', 'a', 'b', 'inter']
['__builtins__', '__doc__', '__file__', '__name__', 'aborg']
['__builtins__', '__doc__', '__file__', '__name__', 'bborg']
>>> inter.x = 123
>>> b.bborg.y = 456
More information about the Python-list