Null-Conditional Assignment Operator (!?=)

[project-x51]

Problem:

In C#, assigning a value to a property of an object requires an explicit null check if the object might be null, leading to verbose code. For example:

if (obj?.Property != null)
    obj.Property.Value = source?.Value;

This pattern is common when working with nested objects or nullable references, and it clutters code with repetitive null checks.

Proposal:

Introduce a null-conditional assignment operator (!?=) that performs an assignment only if the left-hand side is not null. The syntax would look like:

obj?.Property.Value !?= source?.Value;

This would be equivalent to:
If obj?.Property is not null, assign source?.Value to obj.Property.Value.
If obj?.Property is null, skip the assignment.

Example:

Current code:

if (_ThermometerPainter.TopBottom.High != null)
    _ThermometerPainter.TopBottom.High.Icon = this.MinMax?.High?.Icon;

With !?=:

_ThermometerPainter.TopBottom.High?.Icon !?= this.MinMax?.High?.Icon;

This reduces boilerplate and improves readability while maintaining null safety.

Benefits:

• Simplifies common null-conditional assignment patterns.
• Aligns with the null-conditional operator (?.) for a consistent null-handling experience.
• Reduces code verbosity, especially in codebases with frequent null checks.

Discussion:

I believe this operator would streamline null-safe assignments and reduce code. Has this been considered before? Are there edge cases or syntax conflicts to address? I’d love feedback from the community and the C# team!

[CyrusNajmabadi]

obj?.Property.Value = source?.Value;

Simply becomes legal in c#14. It's a feature we are already shipping (and have implemented) for that release.

[project-x51]

Awesome. I'm looking forward to that. :)