overriding

问题 I want to be able to intercept variable assignments within a function and execute custom code. I have tried creating a custom dict as follows: class userdict(dict): def __setitem__(self, key, value): print 'run my code' dict.__setitem__(self, key, value) If I exec code using this as the global dict, then my custom code will run on each variable assignment. e.g.: UserDict = userdict() exec 'x = 1' in UserDict #outputs 'run my code' But if my code is inside a function, it doesn't work: code = "

问题 I have the following: type Base struct { } func(base *Base) Get() string { return "base" } func(base *Base) GetName() string { return base.Get() } I want to define a new type with a new implementation of Get() so that I can use the new type in place of Base and where GetName() is called it calls the new Get() implementation . If I were using Java I would inherit Base and override Get(). How should I achieve this in Go? I want to avoid breaking changes if possible, so existing consumers of

问题 This question already has answers here : Java: How to find if a method is overridden from base class? [duplicate] (8 answers) Closed 2 years ago . I'm receiving an Object and need to log it. Some of them have cusom toString() and then I'd like to use that, but some have none and I get something like mightypork.rogue.bus.events.MouseMotionEvent@2d19587d . I'm looking for a way to dynamically (perhaps with reflection?) check if the incoming object has toString() overridden itself. String

问题 I'm trying to override save() in R so that it creates any missing directories before saving an object. I'm having trouble passing an object through one function to another using the ellipsis method. My example: save <- function(...,file){ #Overridden save() target.dir <- dirname(file) #Extract the target directory if(!file.exists(target.dir)) { #Create the target directory if it doesn't exist. dir.create(target.dir,showWarnings=T,recursive=T) } base::save(...,file=file.path(target.dir

问题 I have these: public class TennisPlayer { } public class RogerFederer : TennisPlayer { } public class RafaelNadal : TennisPlayer { } And then I have some classes with methods, like these: public abstract class Manager { protected abstract void ScheduleFriendlies(TennisPlayer player); } public class RafaelNadalManager : Manager { public void ScheduleFriendlies(RafaelNadal rn) { //throw new NotClayException(); } } public class RogerFedererManager : Manager { public void ScheduleFriendlies

问题 Why does this happen? http://coliru.stacked-crooked.com/a/e1376beff0c157a1 class Base{ private: virtual void do_run() = 0; public: void run(){ do_run(); } }; class A : public Base { public: // uplift ?? virtual void do_run() override {} }; int main() { A a; a.do_run(); } Why can I override a PRIVATE virtual method as public? 回答1: According to https://en.cppreference.com/w/cpp/language/virtual#In_detail overwriting a base's virtual member function only care about the function name, parameters,

问题 I've a base class that implements an extension that conforms to a protocol as below: protocol OptionsDelegate { func handleSortAndFilter(opt: Options) } extension BaseViewController: OptionsDelegate { func handleSortAndFilter(opt: Options) { print("Base class implementation") } } I've a subclass "InspirationsViewController" that inherits from BaseViewController. And I'm overriding protocol method in the extension as below: extension InspirationsViewController { override func

问题 This question already has answers here : Closed 8 years ago . Possible Duplicate: When do you use Java's @Override annotation and why? I wonder what the functionality of adding @Override in front of the code we would like to override is. I have done with and without it, and it seemed that everything was just going well (at least, for me). 回答1: It is not necessary , but it is highly recommended. It keeps you from shooting yourself in the foot. It helps prevent the case when you write a

问题 I am using ViewPager with some Fragments. I would like to achieve the next little effect: if I swipe to the very first page of the viewpager (so the index of the page equals 0), i would like to recreate it. So I do not want it to be pulled from the memory, I would like like to recreate it every time I swipe to that page. I read that I needed to override the instantiateItem method, but I cannot do it. public class PagerAdapter1 extends FragmentPagerAdapter { private List<String> fragments;

问题 I'm trying to override the base layout of FOSUserBundle using the 'simple' option of making a cloned path as .app/Resources/FOSUserBundle/views/layout.html.twig , but symfony2.6 continues to render the template from inside the vendor directory. My composer requires: "require": { "php": ">=5.3.3", "symfony/symfony": "2.6.*", "doctrine/orm": "~2.2,>=2.2.3,<2.5", "doctrine/dbal": "<2.5", "doctrine/doctrine-bundle": "~1.2", "twig/extensions": "~1.0", "symfony/assetic-bundle": "~2.3", "symfony