class-design

问题 I'm trying to understand a bit how Python (2.6) deals with class, instances and so on, and at a certain point, I tried this code: #/usr/bin/python2.6 class Base(object): default = "default value in base" def __init__(self): super(Base, self).__init__() @classmethod def showDefaultValue(cls, defl = default): print "defl == %s" % (defl) class Descend(Base): default = "default value in descend" def __init__(self): super(Descend, self).__init__() if __name__ == "__main__": Descend

来源： https://stackoverflow.com/questions/2301325/when-to-make-class-and-function

来源： https://stackoverflow.com/questions/3308792/python-object-layout

问题 I have a class like this: public class Empresa { public string Nombre { get; set; } public string NIT { get; set; } public string NombreRepresentanteLegal { get; set; } public string TelefonoRepresentanteLegal { get; set; } public string NombreContacto { get; set; } public string TelefonoContacto { get; set; } } However in my app, I want the users to be able to add custom properties, for example twitter handle, however I havent found documentation in how to do that, I heard about the EAV

问题 The problem is quite simple. If a class B inherit a class A and wants to override a ´classmethod´ that is used as a constructor (I guess you call that a "factory method"). The problem is that B.classmethod will want to reuse A.classmethod , but then it will have to create an instance of the class A, while it subclasses the class A - since, as a classmethod, it has no self. And then, it doesn't seem the right way to design that. I did the example trivial, I do more complicate stuff by reading

问题 I have a class diagram , I want that to draw it in some tool which can generate native C++ out of it , I wish to have design first approach to test the various data structures I am designing for my application 回答1: A lot of tools can make C++ code out of UML diagrams. Try Software Ideas Modeller for example, it's a great UML tool, and it's free for non-commercial use. Also, wiki has a list of UML tools. You can sort them by "languages generated" column to check what they do support and chose

问题 I'm interested in hearing some discussion about class attributes in Python. For example, what is a good use case for class attributes? For the most part, I can not come up with a case where a class attribute is preferable to using a module level attribute. If this is true, then why have them around? The problem I have with them, is that it is almost too easy to clobber a class attribute value by mistake, and then your "global" value has turned into a local instance attribute. Feel free to

问题 I'm interested in hearing some discussion about class attributes in Python. For example, what is a good use case for class attributes? For the most part, I can not come up with a case where a class attribute is preferable to using a module level attribute. If this is true, then why have them around? The problem I have with them, is that it is almost too easy to clobber a class attribute value by mistake, and then your "global" value has turned into a local instance attribute. Feel free to

问题 I encountered a strange bug in python where using the __new__ method of a class as a factory would lead to the __init__ method of the instantiated class to be called twice. The idea was originally to use the __new__ method of the mother class to return a specific instance of one of her children depending on the parameters that are passed, without having to declare a factory function outside of the class. I know that using a factory function would be the best design-pattern to use here, but

问题 I am just getting started with .NET ORMs, to the point where I haven't even decided between Entity Framework and NHibernate. But in both cases, I'm running into a problem in that they seem to want me to compromise the integrity of my domain model in various ways, especially on finer points of C# object design. This is one of several questions on the subject. I am very used to enforcing immutability on appropriate properties with a pattern that looks like this: public class Foo { private