Edit: The Flutter team has now taken an official stance on the matter and stated that classes are preferable. See https://www.youtube.com/watch?v=IOyq-eTRhvo TL;DR: Prefer using classes over functions to make reusable widget-tree. EDIT: To make up for some misunderstanding: This is not about functions causing problems, but classes solving some. Flutter wouldn’t have StatelessWidget if a … Read more
myList.GroupBy(test => test.id) .Select(grp => grp.First()); Edit: as getting this IEnumerable<> into a List<> seems to be a mystery to many people, you can simply write: var result = myList.GroupBy(test => test.id) .Select(grp => grp.First()) .ToList(); But one is often better off working with the IEnumerable rather than IList as the Linq above is lazily … Read more
All we know is “All instances of a any class shares the same java.lang.Class object of that type of class” e.g) Student a = new Student(); Student b = new Student(); Then a.getClass() == b.getClass() is true. Now assume Teacher t = new Teacher(); without generics the below is possible. Class studentClassRef = t.getClass(); But … Read more
Unix On Linux, other Unix variants, Git Bash on Windows, or Cygwin, use the jar (or unzip -v), grep, and find commands. The following lists all class files that match a given name: for i in *.jar; do jar -tvf “$i” | grep -Hsi ClassName && echo “$i”; done If you know the entire list … Read more
Variable set outside __init__ belong to the class. They’re shared by all instances. Variables created inside __init__ (and all other method functions) and prefaced with self. belong to the object instance.
int is a primitive type. Variables of type int store the actual binary value for the integer you want to represent. int.parseInt(“1”) doesn’t make sense because int is not a class and therefore doesn’t have any methods. Integer is a class, no different from any other in the Java language. Variables of type Integer store … Read more
A Python file is called a “module” and it’s one way to organize your software so that it makes “sense”. Another is a directory, called a “package”. A module is a distinct thing that may have one or two dozen closely-related classes. The trick is that a module is something you’ll import, and you need … Read more
For a detailed explanation, please see the heading “Avoid Duplication in const and Non-const Member Function,” on p. 23, in Item 3 “Use const whenever possible,” in Effective C++, 3d ed by Scott Meyers, ISBN-13: 9780321334879. Here’s Meyers’ solution (simplified): struct C { const char & get() const { return c; } char & get() … Read more
It’s a “pointer to member” – the following code illustrates its use: #include <iostream> using namespace std; class Car { public: int speed; }; int main() { int Car::*pSpeed = &Car::speed; Car c1; c1.speed = 1; // direct access cout << “speed is ” << c1.speed << endl; c1.*pSpeed = 2; // access via pointer … Read more
What you are asking for is called multiple dispatch. See Julia language examples which demonstrates different types of dispatches. However, before looking at that, we’ll first tackle why overloading is not really what you want in Python. Why Not Overloading? First, one needs to understand the concept of overloading and why it’s not applicable to … Read more