Yet one singleton realization on Python without metaclass. Singleton may has __init__ method which will call only when first object create.
Python, 25 lines
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Copy to clipboard1 2 3 4 5 6 7 8 9 10 11 12 13 14 15 16 17 18 19 20 21 22 23 24 25 | class Singleton(object):
def __new__(cls,*dt,**mp):
if not hasattr(cls,'_inst'):
cls._inst = super(Singleton, cls).__new__(cls,dt,mp)
else:
def init_pass(self,*dt,**mp):pass
cls.__init__ = init_pass
return cls._inst
if __name__ == '__main__':
class A(Singleton):
def __init__(self):
"""Super constructor
There is we can open file or create connection to the database
"""
print "A init"
a1 = A()
a2 = A()
|
Tags: initialization, singleton
