The following is my implementation (and a usage example) of a singleton I use regularly:
try: from PyQt5.QtCore import pyqtWrapperType
except ImportError:
from sip import wrappertype as pyqtWrapperType
class Singleton(pyqtWrapperType, type):
def __init__(cls, name, bases, dict):
super().__init__(name, bases, dict)
cls.instance=None
def __call__(cls,*args,**kw):
if cls.instance is None:
cls.instance=super().__call__(*args, **kw)
return cls.instance
if __name__=="__main__":
from PyQt5.QtCore import QObject, pyqtSlot, pyqtProperty
class MyObject(QObject, metaclass=Singleton):
def __init__(self, parent=None, **kwargs):
super().__init__(parent, **kwargs)
self._x=0
def x(self): return self._x
@pyqtSlot(int)
def setX(self, x): self._x=x
x=pyqtProperty(int, x, setX)
print(MyObject().x)
MyObject().x=1
print(MyObject().x)
I've actually shared this example/technique so many times now that I just quickly created a git repo (https://github.com/jazzycamel/PyQt5Singleton) and a PyPi package (https://pypi.python.org/pypi/PyQt5Singleton) so you can just install it via pip:
$ pip install PyQt5Singleton
and use it (as above):
from PyQt5.QtCore import QObject, pyqtSlot, pyqtProperty
from PyQt5Singleton import Singleton
class MyObject(QObject, metaclass=Singleton):
def __init__(self, parent=None, **kwargs):
super().__init__(parent, **kwargs)
self._x=0
def x(self): return self._x
@pyqtSlot(int)
def setX(self, x): self._x=x
x=pyqtProperty(int, x, setX)
if __name__=="__main__":
print(MyObject().x)
MyObject().x=1
print(MyObject().x)
Hope this helps :)
