C# copying an immutable struct with modification?-CodePudding

Update: I'm using Unity 2020 so only have access to .Net 4

I have several immutable structs that contain info e.g.

public struct Human {
  public readonly string Name;
  public readonly string Age;
  // ... 50 other variables that describe a human
}

Now I want to clone a Human struct, but change 1 value only. I can of course do it like this:

var newSelf = new Human(
  oldSelf.Name,
  oldSelf.Age   1,
  // ... 50 more lines here
)

But as you can see it'll be really tedious to type oldSelf.XYZ 50 times for every single struct I made.

So I'm looking for something like this:

// copy all variable from oldSelf to a new struct, but change the name and increase Age by 1
var newSelf = oldSelf.CloneWithModification(("Name", "Valeria"), ("Age", oldSelf.Age   1));

I am not too keen on a struct precisely. What I need is actually just:

An immutable type that can be passed to another module (without worrying about the receiver modifying content affecting sender).
Easy cloning with small modifications.

CodePudding user response：

You can use records, introduced in C# 9, or if being a value type is also a requirement, use record structs, introduced in C# 10.

public record Human {
  public string Name { get; init; }
  public int Age { get; init; }
  // ... 50 other variables that describe a human
}

Then you can use the with expression to create a copy of a Human, with only some properties changed. Note that this uses the init accessor.

Human human = ...
var newHuman = human with { Age = human.Age   1 }; // this creates a copy

CodePudding user response：

I do not know if this is the answer to your question. But I suggest you run this method to solve the problem. Delete readonly first if not necessary.

public struct Human {
    public string Name;
    public int Age;
}

Create a default value of the variables as oldSelf and then get clones of it.

public void Start()
{
    var oldSelf = new Human
    {
        Name = "Human",
        Age = 56
    };

    var clone1 = oldSelf;
    clone1.Name = "Black "   clone1.Name;
    
    var clone2 = oldSelf;
    clone2.Age  ;

    Debug.Log(clone1.Name); // Black Human
    Debug.Log(clone2.Age); // 57
}

CodePudding user response：

Without using record you can follow the following pattern

public Human WithName(string value)
   => value == Name
      ? this
      : new Human(value, Age, ...);

public Human WithAge(int value)
   => value == Age
      ? this
      : new Human(Name, value, ...);

...