class

问题 This question already has answers here : Why is there no universal base class in Swift? (2 answers) Closed 2 years ago . The Apple's developer documentation says: NSObject is The root class of most Objective-C class hierarchies, from which subclasses inherit a basic interface to the runtime system. I wonder what is the root class of all classes in Swift in the example below: class MyClass { .... } 回答1: Swift classes do not inherit from a universal base class. Classes you define without

问题 I'm having a class Main (which has public static void main(String []args) )and another class MyDocument . There is a variable text present in the Main class which I want to access from a function alphabetOccurrence() present in the MyDocument class. How do I do this? I don't want to use it as a static variable. And any changes can be done only in the function, rest of the code should be untouched. import java.util.*; class Main { public static void main(String[] args) { MyDocument document =

问题 Why class variable in ruby does not behave like static variable, how can I access it simply by doing Mytest.value, instead of MyTest.new.value? class MyTest @@value=0 def value @@value end end puts MyTest.new.value 回答1: You want something like class MyTest @@value = 0 def self.value @@value end end The self makes it a class method, which the class calls directly. 回答2: [EDIT] Read comments to know why not doing this. class MyTest @value=0 class << self attr_accessor :value end end Instead, if

问题 I have a function that only needs to access one value inside an object with has initializers. ImageUploadManager().sendImages(self.images, postID: postID, image: Media().postImage) However doing so yields the following error: Cannot invoke initializer for type 'Media' with no arguments So my question is: is it possible to access a value as I do here withought having to initialize? 回答1: All that needs to be done is to declare a init withough any paramaters: class Media: NSObject { override

问题 I worked on this all day and am stuck on my logic in how I approached this problem. Whenever I have a Vector<class> blah . And I try to blah.push_back(class()) , it doesn't, update or work. I've been researching and I think it has to do with pointers and references. I tried changing Vector<Student> blah to Vector<Student*> blah , and using 'new' Student() when I'm pushing it back, but it still yields the same result. I think I'm defining the vectors wrong. #include "std_lib_facilities.h"

问题 I want to create a class that automatically adds a holder for values that I can access in the future so that when I run cd.orders or cd.users it will return or give me a dataframe of each of the tables I just queried against. Heres my sample code: class samplecode: def __init__(self,credentials): c = credentials ('DATABASE', 'USER', 'PASSWORD', 'HOST', 'PORT', 'SCHEMA') print('credentials loaded') self.connection_string = "postgresql://%s:%s@%s:%s/%s" % (c.USER, c.PASSWORD, c.HOST, str(c.PORT

问题 i want to make my own class to make my code useful and easy. i want to replace (for example) $facebook->api('/me'); to $myclass->me(); to post on wall for example i need to write $facebook->api('/me/feed','post',$atch); i want to make it $myclass->msg($msg); how can i make my own class using facebook class (and i using another DB class) thanks for halp 回答1: Option #1 - quick, easy, common practice for OOP class myFacebook extends facebook { public function me() { return $this->api('/me'); }

问题 I am trying to create a new C++ class in Netbeans, by right-clicking on the virtual 'Source Files' folder inside Netbeans, and clicking on 'New C++ Class'. I name the source file test.cpp and the header file test.hpp. When I click finish, Netbeans complains test.hpp already exists. I go to /home//NetBeansProjects/ and I can see Netbeans did create the file test.hpp. I delete it, try to create a new class again, and same error occurs. Netbeans did create the file again. (The file does not show

问题 I have a namespace in which I'd like to define a class. The class is rather complex so I'd rather define it in a separate header file, but even the simplest code gives me an "undefined reference" error. main.cpp #include <iostream> namespace A { #include "C.hpp" } int main() { A::C foo; std::cout << foo.member << std::endl; return 0; } C.hpp class C { public: C(); int member; } C.cpp C::C() { this->member = 10; } When I run g++ C.cpp main.cpp I get "main.cpp:(.text+0x10): undefined reference

问题 I have a namespace in which I'd like to define a class. The class is rather complex so I'd rather define it in a separate header file, but even the simplest code gives me an "undefined reference" error. main.cpp #include <iostream> namespace A { #include "C.hpp" } int main() { A::C foo; std::cout << foo.member << std::endl; return 0; } C.hpp class C { public: C(); int member; } C.cpp C::C() { this->member = 10; } When I run g++ C.cpp main.cpp I get "main.cpp:(.text+0x10): undefined reference