I am trying to create a Singleton SafeConfigParser object to use across all the
various scripts in this application.
I tried a Singleton pattern found on the web:
<pre>
class Singleton(object):
def __new__(cls):
if not hasattr(cls, '_inst'):
print "Creating Singleton Object"
cls._inst = super(Singleton, cls).__new__(cls)
else:
print "Returning established Singleton"
return cls._inst
import ConfigParser
class Options(ConfigParser.SafeConfigParser, Singleton):
def __init__(self):
print "Initialing Options"
ConfigParser.SafeConfigParser.__init__(self)
self.add_section('test')
</pre>
And this doesn't work because it calls the __init__ method every time I create
the Options object:
<pre>
O = Options()
print O
O.set('test','start','True')
print "from O", O.options('test')
P = Options()
print P
print "from P", P.options('test')
</pre>
This results in:
<pre>
Creating Singleton Object
Initialing Options
<__main__.Options object at 0x02BF4C50>
from O ['start']
Returning established Singleton
Initialing Options
<__main__.Options object at 0x02BF4C50>
from P []
</pre>
I have seen older posts in this group that talk about using modules as
singletons, but this, unless I misunderstand, requires me to code the entire
API for SafeConfigParser in the module:
<pre>
import ConfigParser
class Options(ConfigParser.SafeConfigParser):
def __init__(self):
ConfigParser.SafeConfigParser.__init__(self)
self.readfp(open('defaults.cfg'))
self.read(['local.txt', 'local.cfg'])
def save(self):
with open('local.txt','w') as f:
self.write(f)
__options = Options()
def set(section, name, value):
return self.__options.set(section, name, value)
def options(section):
return self.__options.options
# And so on
</pre>
This seems incredibly wasteful, and to introspect my options I get a module,
not a SafeConfigParser object, so I'm wondering if there is a different way to
handle this?
Josh
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