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Questions tagged [shallow-copy]

A shallow copy of an object is a duplicate that may not be fully independent of the original, in the sense that any references / pointers it holds to other objects refer to the same objects that the original's do. Use this tag for questions regarding implementing or using shallow copying methods.

Shallow copying is a process by which an object is duplicated to create a copy that may not be wholly independent of the original. Also known as "field by field" copying, this differs from deep copying with respect to the treatment of references / pointers to other objects: shallow copying copies the references / pointers held by the original, whereas deep copying makes a deep copy of each referenced object, too. Shallow copying is "shallow" in the sense that it copies only the original object itself, not any appearing deeper in its reference graph.

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Javascript Shallow copy of an object is undefined?

I just started learning Javascript about a week ago so bear with me. I am attempting to make a basic physics engine using a quadtree and nodes as the backing structure for all objects. However in this snippet of code 102 Quadtree.prototype.insert=…
jknam
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Networkx copy clarification

According the doc, it appears that the networkx.copy method does a deep copy of the graph. I'm most concerned about the statement This makes a complete copy of the graph including all of the node or edge attributes. Is this suggesting that it…
sedavidw
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Java: Copy attributes from one object instance to another?

Say you have public class Car{ private Engine m_eng; public Car(){ } public Engine getEngine(){ return m_eng; } public void setEngine(Engine engine){ m_eng = engine; } } public class Engine{ private String m_name; …
u19964
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Deep Copy and Shallow Copy Java

I am studying for a java exam and what I found out practically differed from what is taught in theory. Below is code: StringBuilder num3[]= new StringBuilder[2]; num3[0]= new StringBuilder("Pine"); num3[1]= new StringBuilder("Oak"); …
HereToLearn
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Expression: _BLOCK_TYPE_IS_VALID(pHead->nBlockUse) Error

This error occurs during run time, and I'm not sure what's causing it - the code looks correct to me. #include #include using namespace std; struct Room { int d_noSeat; bool d_hasProjector; Room() = default; …
Will
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Does the default Assignment operator create memory leak, when shallow-copying pointers?

I'm new to this website, and to the programming world. So, please be patient with me :) I read about the rule of three, and I understood how the Copy Constructor and the Assignment operator work. So I understood that, the default ones, provided by…
xPlay
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Shallow/deep copy of std::map

How would I best implement these? I thought of something like this: using namespace std; shape_container shape_container::clone_deep () const { shape_container* ptr = new shape_container(); copy( data.begin(),…
Patrick Oscity
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how to create deep copies of structures

How do I copy a structure in Common Lisp? I created a structure like: (defstruct state board player previous-move depth) Board is a 2 dimension array. I tried doing: (setf new-state state) When I change something in new-state, the changes in…
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Enum type reference or primitive (with example) - shallow/deep copy

My question is very basic, but I would like to understand everything in 100%. Many questions in SO referes to my post, but I haven't find a satisfying answer. We know that Enums in java are reference type. Let's consider the following…
radekEm
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Why does copy of the List still change properties in the original List using C#

Lets say I have this class public class Employee { public string FirstName { get; set; } public string LastName { get; set; } public bool isActive { get; set; } } And use it like this: List Employees = new…
user850010
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Java: Vector add function is it shallow?

When you use the add function to add an object to a vector, is it a shallow copy or deep copy? If it's shallow it means if you change the objects in the vector you would change the original copy of the object?
roverred
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Does stl library use malloc while copying pointers?

I have a question regarding copying pointers in the stl library. Say I define: struct A{ int x; } std::map map1; I then populate map1 using memory from the heap using malloc for the pointer to A. Then I do std::map…
crystalbass17
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Construct Delegate from Delegate. What does the new Delegate Point to?

Consider the following: Action a1 = new Action(_insert); Action a2 = new Action(a1); What is a2 referring to ? Is it a1, a shallow copy of a1 or is it a deep copy of a1 ?
marc wellman
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Copy constructor c++ weird behavoir?

Hi I have a class which includes an array, I'm not passing this through my class constuctor (could be going wrong here?) The array is just defined in the class then initialized in a read method. But in the main I make an instance of the class…
rx432
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python deepcopy and shallow copy and pass reference

A question about python deepcopy and shallow copy. the post at What is the difference between a deep copy and a shallow copy? cannot help me. why e.g. 1 's sum is 6 not 10 ? e.g.1 : kvps = { '1' : 1, '2' : 2 } theCopy = kvps.copy() # both point…
user1002288
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