Conditional not-null assignment operator

[QuAzI]

It would be nice to have an operator to simplify object field filling for PATCH purposes. For example, I have hundreds of lines where I need to check if the target parameter received from the client

if (parameters.x != null)
{
    object.x = parameters.x;
}

It should return the value of the right-hand operand if it isn't null (exists)
for example, AI suggests that Ruby has at least two ways to check value

x = value unless value.nil?
x = value if value != nil

while the most compact option that C# allows is

x = value ?? x;

And it doesn't look good and raises questions from teammates, like why do we have to assign x with the same value if value is null?

It would be nice to have some syntax sugar like

x ?:= value;  // assign value to x only if value is not null

the way similar to the null-coalescing assignment operator ??= provided in C# 8.0

or maybe someone can provide a good example of how to do it without extra overhead and code spaghetti

[Richiban]

Is x = value if value != nil really better than if (value != null) x = value;? Postfix-if has been requested before and rejected.

I'd also add (and I mean this in the nicest possible way) that if teammates find the existing way of x = value ?? x; weird then the appropriate action might be to educate your teammates, rather than requesting a change to the language.

[QuAzI]

It's just a sample from Ruby. The proposal is different.

appropriate action might be to educate your teammates, rather than requesting a change to the language

Can you please describe in the best way why someone has to assign x to x while x already has the same value? I will definitely show it to everyone)
I am also pretty sure that IL code for the new 'short' version can be simpler/faster than current implementations

[HaloFour]

The ?? operator doesn't apply to the assignment, it only applies to the expression used in that assignment. The assignment is unconditional.

If you want the assignment to be conditional, you can already write the following, which is equivalent to the Ruby syntax:

if (value != null) x = value;

[PySom]

already if (value != null) x = value; this is sufficient
Taking advantage of the new language addition null assignment, you could define a dummy extension and do assignment, albeit ugly

A a = new();
B b = new();

a.X?.Value = b.Y = a.X;

Console.WriteLine(a.X);
Console.WriteLine(b.Y);

a.X = "World";
a.X?.Value = b.Y = a.X;

Console.WriteLine(a.X);
Console.WriteLine(b.Y);

static class SomeExtensions
{
    extension<T>(T source)
    {
        public T Value { get => source; set => _ = value; }
    }
}

class A
{
    public string? X { get; set; }
}

class B
{
    public string? Y { get; set; } = "Hello";
}

[full-ing-arr]

may be try use this
x ??= value;

or more evil like this
Do(x ??= value)

[QuAzI]

OMG) It's better for you to not use this op. Try if.