C#•2y ago

❔ Deep clone variable

How to create a complete, isolated copy of a variable to prevent the copy from changing when changed parent variable. I have tried some variants: 1. The most easiest variant

var parent = new Class();
var clonedParent = parent;
// do some changes with parent
if (parent == clonedParent) <-- True

var parent = new Class();
var clonedParent = parent;
// do some changes with parent
if (parent == clonedParent) <-- True

2. Variant with ICloneable *logic still not changed

class Person : ICloneable
{
    public string Name { get; set; }
    public int Age { get; set; }

    public object Clone()
    {
        return new Person { Name = this.Name, Age = this.Age };
    }
}

class Person : ICloneable
{
    public string Name { get; set; }
    public int Age { get; set; }

    public object Clone()
    {
        return new Person { Name = this.Name, Age = this.Age };
    }
}

if (parent == clonedParent) <-- True Still True 3. A little bit harder variant with ICloneable

class myClass : ICloneable
{
    public string Name { get; set; }
    public int Age { get; set; }

    public object Clone()
    {
        return this.MemberwiseClone();
    }
}

class myClass : ICloneable
{
    public string Name { get; set; }
    public int Age { get; set; }

    public object Clone()
    {
        return this.MemberwiseClone();
    }
}

if (parent == clonedParent) <-- True Still True Do you know any other variants to clone and isolate harold

67 Replies

Jimmacle•2y ago

you could use structs which are copied on assignment, or use records that you can copy using with {}

WaffenOP•2y ago

or use records that you can copy using with {} Do you mean this variant?

public object Clone()
    {
        return new Person { Name = this.Name, Age = this.Age };
    }

public object Clone()
    {
        return new Person { Name = this.Name, Age = this.Age };
    }

Jimmacle•2y ago

no, i mean an actual record

ero•2y ago

the Clone() version definitely doesn't return true

MODiX•2y ago

Ero#1111

REPL Result: Success

Person p = new();
Person pCloned = p.Clone() as Person;

Console.WriteLine(p == pCloned);

class Person : ICloneable
{
    public string Name { get; set; }
    public int Age { get; set; }

    public object Clone()
    {
        return new Person { Name = this.Name, Age = this.Age };
    }
}

Person p = new();
Person pCloned = p.Clone() as Person;

Console.WriteLine(p == pCloned);

class Person : ICloneable
{
    public string Name { get; set; }
    public int Age { get; set; }

    public object Clone()
    {
        return new Person { Name = this.Name, Age = this.Age };
    }
}

Console Output

False

False

Compile: 747.068ms | Execution: 94.422ms | React with ❌ to remove this embed.

WaffenOP•2y ago

It is just example My code is too big, i can't send it here

Jimmacle•2y ago

public record SomeRecord(string Name, int Age);

var r1 = new SomeRecord("", 0);
var r2 = r1 with {};

public record SomeRecord(string Name, int Age);

var r1 = new SomeRecord("", 0);
var r2 = r1 with {};

ero•2y ago

well then it's a bad example, no? your "example" works perfectly fine you're newing up the Person. that cannot be equal to the old reference

WaffenOP•2y ago

Let me try

Jimmacle•2y ago

the first "variant" doesn't actually do what's being asked, it's not making a copy

WaffenOP•2y ago

¯\_(ツ)_/¯

ero•2y ago

but this is also flawed because in this instance, r1 == r2 will still be true just beause of a different reason

Jimmacle•2y ago

i interpreted his goal as wanting to make a copy, not just test equality

ero•2y ago

the way it's being tested leads me to believe there's more to this

Jimmacle•2y ago

true, then you'll get a deep copy too

WaffenOP•2y ago

Hm, thanks, let me try record before. But serialize then deserialize method sounds very good.

Jimmacle•2y ago

what are you actually trying to accomplish?

WaffenOP•2y ago

I need to make a copy of the UserProfile then make some changes to it then I need to compare oldProfile and newProfile and get this difference Ok, it doesn't work. It made copy, but it still changes two variables

ero•2y ago

but you made the changes to it, surely therefore you know what differences there are?

Jimmacle•2y ago

idk what you mean by "it changes two variables" it creates a new record with the same values as the first one, it doesn't change anything

WaffenOP•2y ago

Due to some I can't get these changes directly

var r1 = new SomeRecord("", 0);
var r2 = r1 with {};
// do some changes with r2
if (r1 == r2) <-- True

var r1 = new SomeRecord("", 0);
var r2 = r1 with {};
// do some changes with r2
if (r1 == r2) <-- True

Jimmacle•2y ago

that isn't copying anything, classes are by reference

WaffenOP•2y ago

let me try this method firstly

ero•2y ago

what, no try anything else first

Jimmacle•2y ago

this does not mean they are the same object if you want to compare that, use .ReferenceEquals not ==

WaffenOP•2y ago

changed example for you:

var r1 = new SomeRecord("", 0);
var r2 = r1 with {};
// do some changes with r2
if (r1 == r2) <-- True

var r1 = new SomeRecord("", 0);
var r2 = r1 with {};
// do some changes with r2
if (r1 == r2) <-- True

ero•2y ago

this means they have the identical contents

MODiX•2y ago

Ero#1111

REPL Result: Failure

R r1 = new("Foo", 123);
R r2 = r1 with {};

return (r1, r2, r1 == r2, r1.ReferenceEquals(r2));

record R(
  string Name,
  int Age);

R r1 = new("Foo", 123);
R r2 = r1 with {};

return (r1, r2, r1 == r2, r1.ReferenceEquals(r2));

record R(
  string Name,
  int Age);

Exception: CompilationErrorException

- There is no argument given that corresponds to the required parameter 'objB' of 'object.ReferenceEquals(object?, object?)'

- There is no argument given that corresponds to the required parameter 'objB' of 'object.ReferenceEquals(object?, object?)'

Compile: 612.249ms | Execution: 0.000ms | React with ❌ to remove this embed.

Jimmacle•2y ago

even so, how does that indicate it "changed two variables"

ero•2y ago

MODiX•2y ago

Ero#1111

REPL Result: Success

R r1 = new("Foo", 123);
R r2 = r1 with {};

return (r1, r2, r1 == r2, object.ReferenceEquals(r1, r2));

record R(
  string Name,
  int Age);

R r1 = new("Foo", 123);
R r2 = r1 with {};

return (r1, r2, r1 == r2, object.ReferenceEquals(r1, r2));

record R(
  string Name,
  int Age);

Result: ValueTuple<R, R, bool, bool>

{
  "item1": {
    "name": "Foo",
    "age": 123
  },
  "item2": {
    "name": "Foo",
    "age": 123
  },
  "item3": true,
  "item4": false
}

{
  "item1": {
    "name": "Foo",
    "age": 123
  },
  "item2": {
    "name": "Foo",
    "age": 123
  },
  "item3": true,
  "item4": false
}

Compile: 572.211ms | Execution: 117.820ms | React with ❌ to remove this embed.

Jimmacle•2y ago

it's just saying the two objects are equal according to the == operator which can be overridden (and is overridden by records to compare them by value) instead of testing something else and making assumptions about other behavior, test the actual behavior you're trying to achieve

cap5lut•2y ago

the with thing will generally only do shallow copies, so probably not whats wanted either

Jimmacle•2y ago

based on the model posted earlier a shallow copy is sufficient

ero•2y ago

ask insufficient questions, get insufficient answers ¯\_(ツ)_/¯

WaffenOP•2y ago

I needed just a method how to do deep copy

ero•2y ago

there's no one correct answer

WaffenOP•2y ago

serialize then deserialize the best method for me i guess.

ero•2y ago

i guess

cap5lut•2y ago

performance wise, its the worst u can do

WaffenOP•2y ago

Yes, but is there any other variants?

ero•2y ago

do it all recursively i guess

WaffenOP•2y ago

I'm not sure if this method is right for my problem

Jimmacle•2y ago

well, you want a deep copy

cap5lut•2y ago

the easiest and most efficient way is to use the 2nd variant, after all u have to take care of references inside ur instances

WaffenOP•2y ago

What "2nd variant" are you talking about?

cap5lut•2y ago

the ICloneable implementation and actually manually creating the copy inside the Clone method

WaffenOP•2y ago

I've tried this variant already, it stil True

ero•2y ago

i quite literally proved that that is not possible

Jimmacle•2y ago

that's not possible

WaffenOP•2y ago

Okey

cap5lut•2y ago

did u make copies of nested of mutable references as well?

Jimmacle•2y ago

== tests reference equality for classes unless overridden you're returning a new object, so it cannot be the same reference

cap5lut•2y ago

well, unless u show exactly what u tried we cant tell what u did wrong, after all u implemented it urself

public class Box : IClonable {
  public List<object> Items { get; set; } = new();
  public object Clone() {
    return new Box { Items = Items }; // this would not be enough
  }
}

var box1 = new Box();
var box2 = box1 as Box;

public class Box : IClonable {
  public List<object> Items { get; set; } = new();
  public object Clone() {
    return new Box { Items = Items }; // this would not be enough
  }
}

var box1 = new Box();
var box2 = box1 as Box;

here u have only a shallow copy, because box1.Items and box2.Items would reference the same List<object> instance. u would have to make a copy of the list as well. and then u need to think about if need to make a copy of each element in the list as well, and then again if take care about their references

WaffenOP•2y ago

Thanks a lot! I did not know how to correctly formulate my problem, what to correctly google the solution. Deep clone through Serialize and deserialize helps me and takes 0.0758792 seconds. For my project, this delay is not a problem.

Jimmacle•2y ago

i'm not sure how you benchmarked it but i'm very skeptical it took 70ms to serialize and deserialize a 2 field class you should use something like https://benchmarkdotnet.org/

cap5lut•2y ago

different hardware would give different results, also the (de-)serialization methods

Jimmacle•2y ago

not 70ms different that sounds way too high

cap5lut•2y ago

wouldnt alone reflection based and source generation based make quite a huge difference? also the difference is currently 6ms and we dont know the actual structure of the data they tested with

ero•2y ago

It's just user data, it can't be that much Unless the project or game is already hugely complex

Ryada•2y ago

Isn't it easier at all to just get the difference before adjusting an object? Or just newing up an object with replacements in the way of

var secondProfile = new Profile()
{
  Name = oldProfile.Name,
  Rank = oldProfile.Rank,
  Experience = newExperience ?? oldProfile.Experience,
};

var secondProfile = new Profile()
{
  Name = oldProfile.Name,
  Rank = oldProfile.Rank,
  Experience = newExperience ?? oldProfile.Experience,
};

ero•2y ago

that's essentially what the record suggestion was

Profile p1 = new();
Profile p2 =  p1 with
{
  Experience: newExperience ?? oldProfile.Experience
};

Profile p1 = new();
Profile p2 =  p1 with
{
  Experience: newExperience ?? oldProfile.Experience
};

Ryada•2y ago

Ah I missed that one then my bad was a lot of messages

DaVinki•2y ago

What’s wrong with the 2nd option? Why did they resort to serializing and deserializing?

ero•2y ago

nobody knows

cap5lut•2y ago

more to write i guess 😂

Accord•2y ago

Was this issue resolved? If so, run /close - otherwise I will mark this as stale and this post will be archived until there is new activity.

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❔ Deep clone variable