singleton_meta (v0.1.3)

DESCRIPTION_SHORT

create perfect singletons

DESCRIPTION_LONG

designed for singletons creation

Features

1. perfect singleton (maybe thread safe!)
2. collect all instances
3. check correct instantiating singletons in tree project

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License

See the LICENSE file for license rights and limitations (MIT).

Release history

See the HISTORY.md file for release history.

Installation

pip install singleton-meta

Import

from singleton_meta import *

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USAGE EXAMPLES

See tests and sourcecode for other examples.

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1. example1.py

from singleton_meta import *

class MySingleton(SingletonByCallMeta):
    pass

class MySingleton2(SingletonByCallMeta):
    pass

class MySingleton(metaclass=SingletonMetaCallClass):
    pass


# ===============================
# 2. access to created instances
from singleton_meta import *

class Victim1(SingletonByCallMeta):
    attr = 1

class Victim2(SingletonByCallMeta):
    attr = 2

assert SingletonByCallMeta._SINGLETONS == []
Victim1()
assert SingletonByCallMeta._SINGLETONS == [Victim1(), ]
assert Victim1._SINGLETONS == [Victim1(), ]
assert Victim1()._SINGLETONS == [Victim1(), ]
Victim2()
assert SingletonByCallMeta._SINGLETONS == [Victim1(), Victim2(), ]


# ===============================
# 3. NOTICE: all your Singletons must be only last classes!
# don't use nesting from any Your Singletons!
from singleton_meta import *

class MySingleton(SingletonByCallMeta):  # OK
    pass

class MySingleton2(MySingleton):  # WRONG
    pass

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