C#•16mo ago

❔ how to use "with"

the name with does not exist in the current context

32 Replies

Thinker•16mo ago

That's not how you use with Remove the new Human() after with Although you don't really need with here anyway since this just looks like a regular object initializer

Human human = new Human() { Sex = "female" };

Human human = new Human() { Sex = "female" };

zzzzOP•16mo ago

"not a valid record type"

Thinker•16mo ago

Ah, yeah, with only works on records and structs

zzzzOP•16mo ago

aw 😦 unfortunate

Thinker•16mo ago

Although depends on what your Human class looks like, you could easily convert it to a record with little to no downsides

zzzzOP•16mo ago

zzzzOP•16mo ago

class Human
{
    private string? name;

    public string? Name 
    { 
        get =>  name; 
        set { Console.WriteLine("{0} has decided their name is {1}!", name, value); name = value; } 
    }
    public required string Sex { get; init; }
    protected int Age { get; set; }

    public void Grow()
    {
        Age++;
    }
}

class Human
{
    private string? name;

    public string? Name 
    { 
        get =>  name; 
        set { Console.WriteLine("{0} has decided their name is {1}!", name, value); name = value; } 
    }
    public required string Sex { get; init; }
    protected int Age { get; set; }

    public void Grow()
    {
        Age++;
    }
}

Thinker•16mo ago

You could really just change class to record if you wanted to

zzzzOP•16mo ago

hm yeah, it just amounted to doing that

Thinker•16mo ago

Also while you're at it, use string interpolation instead of that overload of Console.WriteLine And also put the setter on two lines

set
{
    Console.WriteLine($"{name} has decided their name is {value}!");
    name = value;
}

set
{
    Console.WriteLine($"{name} has decided their name is {value}!");
    name = value;
}

zzzzOP•16mo ago

should it be record class instead of just record to ensure its a reference type?

Thinker•16mo ago

record is always a reference type, but you can use record class if you feel it makes it clearer or if you use record structs a lot and you feel the need to clarify between what is a record struct and class

zzzzOP•16mo ago

may i ask for a tldr for what a record is?

Thinker•16mo ago

A record is a regular class or struct but with automatic reference equality, a shorter syntax, and other nicities like with and automatic deconstruction.

zzzzOP•16mo ago

reference equality, meaning that if two records have the same data, they're considered equal?

Thinker•16mo ago

yep classes are by default compared by reference

zzzzOP•16mo ago

what about usual object methods like .Equals() etc

Thinker•16mo ago

those are overwritten by records

zzzzOP•16mo ago

oh, i assume same for ==

Thinker•16mo ago

yep

zzzzOP•16mo ago

before records were introduced what was the way to achieve this functionality? (also sorry for interrupting your explanations all the time)

Thinker•16mo ago

just writing everything out in its entirety records are pretty much just short-hand

public class Person : IEquatable<Person>
{
    public string Name { get; init; }
    public int Age { get; init; }

    public Person(string name, int age)
    {
        Name = name;
        Age = age;
    }

    public bool Equals(Person? other) =>
        other is not null &&
        Name == other.Name &&
        Age == other.Age;
    
    public override bool Equals(object? obj) =>
        Equals(obj as Person);

    public override int GetHashCode() =>
        HashCode.Combine(Name, Age);

    public override string ToString() =>
        $"Person {{ Name = {Name}, Age = {Age} }}";

    public void Deconstruct(out string name, out int age)
    {
        name = Name;
        age = Age;
    }

    public static bool operator ==(Person a, Person b) => a.Equals(b);
    public static bool operator !=(Person a, Person b) => !a.Equals(b);
}

public class Person : IEquatable<Person>
{
    public string Name { get; init; }
    public int Age { get; init; }

    public Person(string name, int age)
    {
        Name = name;
        Age = age;
    }

    public bool Equals(Person? other) =>
        other is not null &&
        Name == other.Name &&
        Age == other.Age;
    
    public override bool Equals(object? obj) =>
        Equals(obj as Person);

    public override int GetHashCode() =>
        HashCode.Combine(Name, Age);

    public override string ToString() =>
        $"Person {{ Name = {Name}, Age = {Age} }}";

    public void Deconstruct(out string name, out int age)
    {
        name = Name;
        age = Age;
    }

    public static bool operator ==(Person a, Person b) => a.Equals(b);
    public static bool operator !=(Person a, Person b) => !a.Equals(b);
}

This can be written as

public record Person(string Name, int Age);

public record Person(string Name, int Age);

zzzzOP•16mo ago

o: wow C# is amazing offtopic, but in your opinion, do you think humans are records? if two people have the same name, age

Thinker•16mo ago

Personally I would probably represent a human/person as a record, although depends on how complex you want the structure to be

zzzzOP•16mo ago

hmm.. what would be a quality humans have that makes them unique? their dna? lmao maybe i could give each human a hash

Thinker•16mo ago

Yeah like in the programming sense you could probably assume two people are the same if they have the same values, although if you were to strive for a "complete" model of a human then yeah you'd probably compare by DNA or something

zzzzOP•16mo ago

i see. i guess it would depend on what spec is

Thinker•16mo ago

yeah, usually referred to as "domain modeling"

zzzzOP•16mo ago

thank you!

Thinker•16mo ago

Accord•16mo 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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❔ how to use "with"

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