Hi,

I'm porting a piece of software to FPC but I got stuck at a forward struct declaration. The situation is as folows.

Header 1 declares:
    struct TaskHandle__;
    typedef void (*CallBackProcPtr)(struct TaskHandle__ *task);

And Header2 provdes:
typedef struct TaskHandle__ { int unused; } *TaskHandle

However header 2 already references header 1 because it already contains some other type definitions, so I cannot reference header 2 in header 1 because of a circular dependency. Can FPC do something similar to C and define a forward record?

Regards, Darius

A: You could move the declaration of TaskHandle__ to a common unit which is used by the other two units.

B: As the TaskHandle__ type seems rather simple move it to the Header 1 unit with a comment "was originally declared in Header 1" (because Header 2 already uses Header 1)

C: You could treat the "task" parmeter for the callback simply as a pointer... (of course you reduce static typing with this)

Regards,
Sven

No. What you can do is merge the headers in a single unit: PTaskHandle__ = ^TTaskHandle__;
and define TTaskHandle__ in the same block

The CallBackProcPtr only needs a pointer, so you could also simply define a pointer.

Michael.

Thanks Sven and Michael,

I will do as you proposed and simply use a pointer for now. Later once the code has been ported I will have a look to refactor the code.

Regards, Darius