As Delphi allows to forward declare both classes and interfaces, people often wonder about records.

The short answer: you can’t forward declare record types.

The long answer: you can’t directly, but you can indirectly either reference based (through pointers or callbacks with const parameters) or operator based (through operator overloading).

I think the reason forward declaration of classes and interfaces is possible because they both are reference types, so referring does not impose copying.

Anyway, the trick is this:

You can’t have forward declarations for record types. Define both Implicit operators in the second type Source: delphi – How do I define implicit conversion operators for mutually dependent records? – Stack Overflow

–jeroen

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