If you call the SpecificError class it will look for an __init__. If it doesn’t exist it will call the parent’s __init__. There is no need to add an __init__ here, since it’s exactly the same like the parent class. It is basically code duplication. You should do: class SpecificError(MyProjectExceptions): “””Raise when a specific error … Read more
CPython’s bug tracker’s issue 805304, “super instances don’t support item assignment”, has Raymond Hettinger give a detailed explanation of perceived difficulties. The reason this doesn’t work automatically is that such methods have to be defined on the class due to Python’s caching of methods, whilst the proxied methods are found at runtime. He offers a … Read more
In ES6, derived classes have to call super() if they have a constructor. In react, all components extend from the Component class. You don’t actually need a constructor for every ES6/react class. If no custom constructor is defined, it will use the default constructor. For base classes, it is: constructor() {} And for derived classes, … Read more
super is a keyword in Java. It refers to the immediate parents property. super() //refers parent’s constructor super.getMusic(); //refers to the parent’s method – Read More on super
Not in this case. But in general, and especially when you use multiple inheritance, super() delegates to the next object in the Method Resolution Order (MRO) as is specified in the documentation: super([type[, object-or-type]]) Return a proxy object that delegates method calls to a parent or sibling class of type. This is useful for accessing … Read more
Are you reloading modules somehow in the middle of things? If so, that may explain this error. isinstance(self,DBAdminConnection) may become false after reloading modules because of the changes to memory references, apparently. Edit: if you’re running your web.py app under mod_wsgi, make sure you’re disabling autoreload: app = web.application(urls, globals(), autoreload=False)
You can, but you have to override __new__ which is called implicitly before __init__: class Z(X): def __new__(cls, a, b, c, d): self = super(Z, cls).__new__(cls, a, b, c) self.d = d return self >>> z = Z(1, 2, 3, 4) >>> z Z(a=1, b=2, c=3) >>> z.d 4 But d will be just an … Read more
I expected Background init() to be called. To pass “a, b” to Fields init(), Field to assign a and b So far, so good. then to assign a list with three 0’s in it to field. Ah. This is where we get the error. self.field = self.buildField() Even though this line occurs within Field.__init__, self … Read more
The two-argument form is only needed in Python 2. The reason is that self.__class__ always refers to the “leaf” class in the inheritance tree — that is, the most specific class of the object — but when you call super you need to tell it which implementation is currently being invoked, so it can invoke … Read more
super() is not broken — it just should not be considered the standard way of calling a method of the base class. This did not change with Python 3.x. The only thing that changed is that you don’t need to pass the arguments self, cls in the standard case that self is the first parameter … Read more