Bringing C# nullability into existing code - dammit is not the answer! - Maarten Balliauw

• C# nullability is a design-time safety feature, not a runtime safety feature.
• The ? (nullable annotation) can be added to method parameters and return types to indicate that they can be null.
• The nonnull attribute can be used to explicitly specify that a property or field cannot be null.
• The ? (nullable annotation) can be used to make a non-nullable reference type nullable, but this is generally considered an anti-pattern and should be avoided.
• The compiler and IDE can be configured to control the level of nullability warnings and errors.
• The nullable attribute can be used to specify that a property or field can be null.
• The required keyword can be used to specify that a property or field cannot be null.
• The nullable context attribute can be used to specify the nullability context for a project or solution.
• The ? (nullable annotation) can be used to specify that a parameter or return type can be null, but the compiler and IDE will not perform any additional checks.
• The nodiscard attribute can be used to specify that a property or field will always return a non-null value.
• The ?? (null-coalescing operator) can be used to provide a default value in case a property or field is null.
• The ??= (null-coalescing assignment operator) can be used to assign a default value in case a property or field is null.
• The ??! (null-coalescing assignment operator) can be used to assign a default value in case a property or field is null.
• The ! (null-forgiving operator) can be used to explicitly specify that a value is not null.
• The ?? (null-coalescing operator) can be used to provide a default value in case a property or field is null.

Note: These are just some key takeaways from the text, and are not necessarily a comprehensive summary of the talk.