A shallow copy just copies the values of the references in the class. A deep copy copies the values. given: class Foo { private Bar myBar; … public Foo shallowCopy() { Foo newFoo = new Foo(); newFoo.myBar = myBar; return newFoo; } public Foo deepCopy() { Foo newFoo = new Foo(); newFoo.myBar = myBar.clone(); //or … Read more
Both of these will give a duplicate of a set: shallow_copy_of_set = set(old_set) Or: shallow_copy_of_set = old_set.copy() #Which is more readable. The reason that the first way above doesn’t give a set of a set, is that the proper syntax for that would be set([old_set]). Which wouldn’t work, because sets can’t be elements in other … Read more
This is a complex subject with lots of possible solutions and many pros and cons to each. There is a wonderful article here that outlines several different ways of making a copy in C#. To summarize: Clone Manually Tedious, but high level of control. Clone with MemberwiseClone Only creates a shallow copy, i.e. for reference-type … Read more
It’s always better to copy using a copy constructor. clone() in Java is broken (see SO: How to properly override clone method?). Josh Bloch on Design – Copy Constructor versus Cloning If you’ve read the item about cloning in my book, especially if you read between the lines, you will know that I think clone … Read more
Use angular.copy when assigning value of object or array to another variable and that object value should not be changed. Without deep copy or using angular.copy, changing value of property or adding any new property update all object referencing that same object. var app = angular.module(‘copyExample’, []); app.controller(‘ExampleController’, [‘$scope’, function($scope) { $scope.printToConsole = function() { … Read more
In PHP 5+ objects are passed by reference. In PHP 4 they are passed by value (that’s why it had runtime pass by reference, which became deprecated). You can use the ‘clone’ operator in PHP5 to copy objects: $objectB = clone $objectA; Also, it’s just objects that are passed by reference, not everything as you’ve … Read more
Breadth vs Depth; think in terms of a tree of references with your object as the root node. Shallow: The variables A and B refer to different areas of memory, when B is assigned to A the two variables refer to the same area of memory. Later modifications to the contents of either are instantly … Read more