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Jeroen W. Pluimers on .NET, C#, Delphi, databases, and personal interests

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Spring4D How to correctly assign NULL to a Nullable type?

Posted by jpluimers on 2018/12/19

Since I tend to forget this: [WayBack] Spring4D How to correctly assign NULL to a Nullable type? this is correct? fDateTime = Null; or this? fDateTime := nil; – Jacek Laskowski – Google+

The preferred way is fDateTime := nil.

This is possible because of [WayBack] Delphi sorcery: How to create an operator overload that only accepts nil using a reference type (in this case interface) so no non-nil pointers can be passed:

type
  Nullable<T> = record
  strict private type
    Null = interface end;
  public
    class operator Implicit(const value: Null): Nullable<T>;
  end;

–jeroen

2 Responses to “Spring4D How to correctly assign NULL to a Nullable type?”

  1. Jacek said

    you often quote me here ;-)

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