Confusion about a syntax in .net

Question

I have got the below code which is compatible in new version. please see & tell me how it works?

DelegateCommand incrementCommand;
    public DelegateCommand IncrementCommand {
        get => incrementCommand ??= new DelegateCommand(Increment, null, true);
    }				
	

i do not understand the meaning of this line get => incrementCommand ??= new DelegateCommand(Increment, null, true);

please tell me what the above line is doing ?

DelegateCommand incrementCommand;
    public DelegateCommand IncrementCommand {
        get => incrementCommand ??= new DelegateCommand(Increment, null, true);
    }	

in which version the above code will compile ?
how to convert the above code in .net version 4.5.2?

looking for help.

Answer 1

??= is the null-coalescing assignment operator, which is a new feature in C# 8, which can only run in .Net Core 3 and later versions.

It returns the value of its left-hand operand if it isn't null; otherwise, it evaluates the right-hand operand and returns its result.

            int? i = 5;  
            Console.WriteLine(i ??= 17); //output  5  
  
            int? j = null;  
            Console.WriteLine(j ??= 17); //output 17  

We can use the ternary conditional operator to replace it in .Net Framework 4.5.

        public DelegateCommand IncrementCommand1  
        {  
            get => incrementCommand != null ? incrementCommand : new DelegateCommand(Increment, null, true);  
        }  

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Answer 2

@T.Zacks

This may clear it up for you.

https://docs.devexpress.com/WPF/17353/mvvm-framework/commands/delegate-commands

https://learn.microsoft.com/en-us/dotnet/csharp/language-reference/operators/lambda-operator

https://learn.microsoft.com/en-us/dotnet/csharp/programming-guide/statements-expressions-operators/expression-bodied-members

the ?? may be place holders. I also think it has to do with WPF and MVVM and the ICommand. So you may want to post to that Q&A tag.