Hafner.Extensions.Object.CheckNull

This micro package provides extension method System.Object.CheckNull() (restricted to reference types).

Description

Package Hafner.Extensions.Object.CheckNull contains an extension method for a System.Object that checks whether it is null (Nothing in Visual Basic) and in case it is, throws an ArgumentNullException with a speaking message (using the automatically filled in 2nd argument parameterName); otherwise, the object is returned.

This method is especially useful in conjunction with C#'s primary constructors where there is no built-in way to check the arguments before they are assigned.

public class Employee(int employeeNo, Person person) { public string EmployeeNo { get; } = employeeNo; public string Person { get; } = person.CheckNull(); }

Behavior and Edge Cases:

• If the object is a System.ValueType it cannot be called (compile error).
• If the object is not null, the same instance is returned.
• If the object is null and the parameter name is null an ArgumentNullException with a generic message is thrown ("The argument is mandatory and cannot be null!")
• If the object is null and the parameter name is recognized as an expression, an ArgumentNullException with an according message is thrown ("The result of the expression '{paramName}' is mandatory and cannot be null!")
• If the object is null and the parameter name is recognized as a parameter name, an ArgumentNullException with an according message is thrown ("The argument for parameter '{paramName}' is mandatory and cannot be null!")

Supported Frameworks:

• .NET Framework versions 2.0, 3.0, 3.5, 4.0, 4.0.3, 4.5, 4.5.1, 4.5.2, 4.6, 4.6.1, 4.6.2, 4.7, 4.7.1, 4.7.2, 4.8, 4.8.1
• .NET Core versions 1.0, 1.1, 2.0, 2.1, 2.2, 3.0, 3.1, 5.0, 6.0, 7.0, 8.0, 9.0, 10.0
• .NET Standard versions 1.0, 1.1, 1.2, 1.3, 1.4, 1.5, 1.6, 2.0, 2.1