Hallo,
playing with the decorators from PEP 318 I found the elegant singleton
decorator.
def singleton(cls):
instances = {}
def getinstance():
if cls not in instances:
instances[cls] = cls()
return instances[cls]
return getinstance
@singleton
class A: pass
class B: pass
a1=A()
a2=A()
a3=A()
b1=B()
b2=B()
b3=B()
for i in ((a1,b1),(a2,b2),(a3,b3)):
print id(i[0]),id(i[1])
But I always get a syntax error declaring class A as singleton.
>>> reload ( decorator)
Traceback (most recent call last):
File "<stdin>", line 1, in ?
File "decorator.py", line 27
class A: pass
^
SyntaxError: invalid syntax
What's the problem with this code because it's only copied for the PEP
318?
It doesn't work with python 2.4 and python 2.5.
Greetings Rainer
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