overriding

问题 I am attempting to override a built in widget template in Django 1.11. I seem to be doing everything that the docs say to do in this regard, but for the widget templates, Django is not looking in my project at all, and I get a TemplateDoesNotExist error. Here's what I have for the override: class MyFileWidget(widgets.FileInput): template_name = 'myapp/my_file_widget.html' The template is definitely there. If I pass the template to a render call, it finds it fine. Problem is an issue of paths.

问题 I've got a class A , which conforms to Equatable protocol and implements == function. In subclass B I override == with more checks. However, when I do comparison between two arrays of instances of B (which both have type Array<A> ), == for A is invoked. Of course if I change type of both arrays to Array<B> , == for B is invoked. I came up with the following solution: A.swift: internal func ==(lhs: A, rhs: A) -> Bool { if lhs is B && rhs is B { return lhs as! B == rhs as! B } return ... }

问题 My view has a white background, and it has to stay that way. I have a TimePicker on that white background.Everything is woking fine with android 2.3.3 but android 4.0.3 has a new timePicker style. The numbers have a very bright color. It is very hard to see them on the white background, and I didn't find a direct way to change the textColor. I don't want to change the background because it would look not so good. Is there any way to override this and set the color of the numbers to black?

问题 I have script wherein basename() is used 100-1000s of time, I was just thinking if we can override the function rather than changing the function name to something else in all scripts. The problem with basename() is that it doesnt works well with names of files in foreign languages. I found one on php site http://php.net/manual/en/function.override-function.php but it needs PECL any other alternative? 回答1: You can use namespaces to override existing function names: namespace blarg; function

问题 The Java compiler doesn't complain when I override a protected method with a public method. What's really happening here? Is it overriding or hiding the parent method since the parent method has lower visibility? 回答1: A sub-class can always widen the access modifier, because it is still a valid substitution for the super-class. From the Java specification about Requirements in Overriding and Hiding: The access modifier (§6.6) of an overriding or hiding method must provide at least as much

问题 I would expect that if foo is declared in class D , but not marked virtual, then the following code would call the implementation of foo in D (regardless of the dynamic type of d ). D& d = ...; d.foo(); However, in the following program, that is not the case. Can anyone explain this? Is a method automatically virtual if it overrides a virtual function? #include <iostream> using namespace std; class C { public: virtual void foo() { cout << "C" << endl; } }; class D : public C { public: void

问题 Consider the following piece of code: class foo { private function m() { echo 'foo->m() '; } public function call() { $this->m(); } } class bar extends foo { private function m() { echo 'bar->m() '; } public function callbar() { $this->m(); } } $bar = new bar; $bar->call(); $bar->callbar(); Now, changing the visibility of the m() method, I get: ( + for public , - for private ) Visibility bar->call() bar->callbar() ====================================================== -foo->m(), -bar->m() foo

问题 I have a custom TagField form field. class TagField(forms.CharField): def __init__(self, *args, **kwargs): super(TagField, self).__init__(*args, **kwargs) self.widget = forms.TextInput(attrs={'class':'tag_field'}) As seen above, it uses a TextInput form field widget. But in admin I would like it to be displayed using Textarea widget. For this, there is formfield_overrides hook but it does not work for this case. The admin declaration is: class ProductAdmin(admin.ModelAdmin): ... formfield

问题 Is there any way to enforce the usage of the C++11 override keyword in Visual C++ 2012? (i.e. if I forget to say override , then I want to get a warning/error.) 回答1: C++11 almost had what you want. Originally the override keyword was part of a larger proposal (N2928) which also included the ability to enforce its usage: class A { virtual void f(); }; class B [[base_check]] : public A { void f(); // error! }; class C [[base_check]] : public A { void f [[override]] (); // OK }; The base_check

问题 I have a base class with a virtual function and I want to override that function in a derived class. Is there some way to make the compiler check if the function I declared in the derived class actually overrides a function in the base class? I would like to add some macro or something that ensures that I didn't accidentally declare a new function, instead of overriding the old one. Take this example: class parent { public: virtual void handle_event(int something) const { // boring default