deep-copy

问题 Regarding to the requirement for C++ stl container element, the standard says: the element type should be CopyConstructible, and there is a table for CopyConstructible requirements. Also by various books (Josuttis, etc.), the generated copy should be "equivalent to" the source. I think I need some clarity here. What is exactly "equivalent to"? Also I am a bit confused with the relation between the "CopyConstructible" and the "deep/shallow copy". In general, a copy constructor is either

问题 Could someone explain how exactly the copy method for Kotlin data classes work? It seems like for some members, a (deep) copy is not actually created and the references are still to the original. fun test() { val bar = Bar(0) val foo = Foo(5, bar, mutableListOf(1, 2, 3)) println("foo : $foo") val barCopy = bar.copy() val fooCopy = foo.copy() foo.a = 10 bar.x = 2 foo.list.add(4) println("foo : $foo") println("fooCopy: $fooCopy") println("barCopy: $barCopy") } data class Foo(var a: Int, val bar

问题 How to copy a "Dictionary" in Swift? That is, get another object with same keys/values but different memory address. Furthermore, how to copy an object in Swift? Thanks, 回答1: A 'Dictionary' is actually a Struct in swift, which is a value type. So copying it is as easy as: let myDictionary = ... let copyOfMyDictionary = myDictionary To copy an object (which is a reference type) has a couple of different answers. If the object adopts the NSCopying protocol, then you can just do: let myObject =

问题 I am working on some code that is written in C#. In this app, I have a custom collection defined as follows: public class ResultList<T> : IEnumerable<T> { public List<T> Results { get; set; } public decimal CenterLatitude { get; set; } public decimal CenterLongitude { get; set; } } The type used by Results are one of three custom types. The properties of each of the custom types are just primitive types (ints, strings, bools, int?, bool?). Here is an example of one of the custom types: public

问题 This question already has answers here : Closed 7 years ago . Possible Duplicate: What's the best way to make a deep copy of a data structure in Perl? Before I start coding this myself and reinventing the wheel, how do you copy a hash of hashes without duplicating the hashrefs? I'm reading a hash of hash of hashes via Config::General. i.e., the data structure is: my %config = ( group => { item1 => { foo => 'value', bar => 'value', }, item2 => { foo => 'value', bar => 'value', }, item3 => {

问题 I am struggling with deep copies of objects in nodeJS. my own extend is crap. underscore's extend is flat. there are rather simple extend variants here on stackexchange, but none are even close to jQuery.extend(true, {}, obj, obj, obj) .. (most are actually terrible and screw up the benefits of asnyc code.) hence, my question: is there a good deep copy for NodeJS? Has anybody ported jQuery's ? 回答1: You want jQuery's, so just use it: function extend() { var options, name, src, copy,

问题 This question already has answers here : how do I measure the memory usage of an object in python? (2 answers) Closed 11 months ago . I want to calculate the memory used by an object. sys.getsizeof is great, but is shallow (for example, called on a list, it would not include the memory taken by the list's elements). I'd like to write a generic "deep" version of sys.getsizeof . I understand there is some ambiguity in the definition of "deep"; I'm perfectly happy with the definition followed by

问题 This question already has answers here : how do I measure the memory usage of an object in python? (2 answers) Closed 11 months ago . I want to calculate the memory used by an object. sys.getsizeof is great, but is shallow (for example, called on a list, it would not include the memory taken by the list's elements). I'd like to write a generic "deep" version of sys.getsizeof . I understand there is some ambiguity in the definition of "deep"; I'm perfectly happy with the definition followed by

问题 I tried to do some operation ( setParent ) on an object in Python (an instance of a class which inherits from a different class - to be specific, QtGui.QLabel ), but during runtime the above error was raised. The object itself has had some fields with actual content (verified on debug), but from some reason I couldn't "use" it. What does the error mean and how can I fix it? For some additional information, I shall say that the object was returned from a static method before I tried to do this

问题 I tried to do some operation ( setParent ) on an object in Python (an instance of a class which inherits from a different class - to be specific, QtGui.QLabel ), but during runtime the above error was raised. The object itself has had some fields with actual content (verified on debug), but from some reason I couldn't "use" it. What does the error mean and how can I fix it? For some additional information, I shall say that the object was returned from a static method before I tried to do this