lsst.ctrl.pool.pool.SingletonMeta Class Reference

Metaclass to produce a singleton. More...

Inheritance diagram for lsst.ctrl.pool.pool.SingletonMeta:

Public Member Functions
def	__init__ (cls, name, bases, dict_)
def	__call__ (cls, *args, **kwargs)

Detailed Description

Metaclass to produce a singleton.

Doing a singleton mixin without a metaclass (via __new__) is
annoying because the user has to name his __init__ something else
(otherwise it's called every time, which undoes any changes).
Using this metaclass, the class's __init__ is called exactly once.

Because this is a metaclass, note that:
* "self" here is the class
* "__init__" is making the class (it's like the body of the
  class definition).
* "__call__" is making an instance of the class (it's like
  "__new__" in the class).

Definition at line 367 of file pool.py.

Constructor & Destructor Documentation

__init__()

def lsst.ctrl.pool.pool.SingletonMeta.__init__	(		cls,
			name,
			bases,
			dict_
	)

Definition at line 383 of file pool.py.

    def __init__(cls, name, bases, dict_):
        super(SingletonMeta, cls).__init__(name, bases, dict_)
        cls._instance = None
 

Member Function Documentation

__call__()

def lsst.ctrl.pool.pool.SingletonMeta.__call__	(		cls,
		*	args,
		**	kwargs
	)

Definition at line 387 of file pool.py.

    def __call__(cls, *args, **kwargs):
        if cls._instance is None:
            cls._instance = super(SingletonMeta, cls).__call__(*args, **kwargs)
        return cls._instance
 
 

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The documentation for this class was generated from the following file:

• /j/snowflake/release/lsstsw/stack/lsst-scipipe-0.7.0/Linux64/ctrl_pool/22.0.1-2-g92698f7+9f079a9461/python/lsst/ctrl/pool/pool.py