singleton pattern for python 2 and 3
Project description
py-singleton
Singleton pattern for python 2 & 3.
Install
pip install py-singleton
Test
in the root folder, run pytest:
pytest
Dependencies
None
unit test needs pytest.
API
-
Apply class decorator singleton to any class;
-
Expected behaviors:
- class can be instantiated as usual, but only one instance is created;
- apis to access the class instance:
@singleton class Server(object): pass srv = Server()
or
srv = Server.instance()
- the function _init_() of decorated class will be called once and only once when the instance is created.
Example
from py_singleton import singleton
@singleton
class A(object):
count = 0
def __init__(self):
A.count += 1
a1 = A()
a2 = A()
a3 = A.instance()
assert A.count == 1
assert a1 is a2
assert a1 is a3
Limitation
For best performance, the code to create instance is not thread-safe, however, after the instance is created it should be safe for multi-threading.
It is recommended to call instance() once during the initial phrase of your app in a single thread.
Project details
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py-singleton-1.0.0.tar.gz
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