I wish to initialize bar to NULL. Is this the best way to do it? It is the correct way. So, yes. Also, is it necessary that the destructor is virtual? No. The destructor only needs to be virtual if you will be inheriting from the Foo class and will be using a Foo pointer … Read more
In fact the difference between adding methods dynamically at run time and your example is huge: in your case, you just attach a function to an object, you can call it of course but it is unbound, it has no relation with the object itself (ie. you cannot use self inside the function) when added … Read more
No, not according to the java language specification, 3rd edition: 6.6.8 Example: private Fields, Methods, and Constructors A private class member or constructor is accessible only within the body of the top level class (ยง7.6) that encloses the declaration of the member or constructor. It is not inherited by subclasses. But regardless of this language … Read more
Interfaces are 100% abstract and the only way to create an instance of an interface is to instantiate a class that implements it. Allowing interfaces to be final is completely pointless. EDIT The questions is not as outright outrageous as I first thought. A final interface is one that cannot be extended by other interfaces … Read more
Python doesn’t have the concept of private methods or attributes. It’s all about how you implement your class. But you can use pseudo-private variables (name mangling); any variable preceded by __(two underscores) becomes a pseudo-private variable. From the documentation: Since there is a valid use-case for class-private members (namely to avoid name clashes of names … Read more
C++ is usually considered a “multi-paradigm” language. That is, you can use it for object-oriented, procedural, and even functional programming. Those who would deny that C++ is OO generally have beef with the fact that the primitive types are not objects themselves. By this standard, Java would also not be considered OO. It is certainly … Read more
Subclassing multiprocessing.Process: However I cannot get back the values, how can I use queues in this way? Process needs a Queue() to receive the results… An example of how to subclass multiprocessing.Process follows… from multiprocessing import Process, Queue class Processor(Process): def __init__(self, queue, idx, **kwargs): super(Processor, self).__init__() self.queue = queue self.idx = idx self.kwargs = … Read more
You can use the ObjectSpace module to do this, specifically the each_object method. ObjectSpace.each_object(Project).count For completeness, here’s how you would use that in your class (hat tip to sawa) class Project # … def self.all ObjectSpace.each_object(self).to_a end def self.count all.count end end
Returning a value is preferable as it allows you to keep all the attribute modifying in one place (__init__). Also, this makes it easier to extend the code later; suppose you want to override _build_query in a subclass, then the overriding method can just return a value, without needing to know which attribute to set. … Read more