Opaque Pointers

[Tom Hanlin]

Yep, it's on the wish list.

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Tom Hanlin
PowerBASIC Staff

[Mark Newman]

Great!

BTW, is something like TYPEDEF on the wishlist? It'd be handy when porting over Windows-C code,
something I seem to be doing a lot of lately

Thanks!

------------------
Mark Newman

[Tom Hanlin]

Should make no noticeable difference.

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Tom Hanlin
PowerBASIC Staff

[Mark Newman]

Hello all,

When dealing with some of the Windows internals, the APIs often use an "opaque pointer", which is a pointer
returned by the API to some unknown (to the client) structure, the details of which are unimportant to the
client. For example, in the SETUPAPI.H file:

   //
   // Define type for reference to device information set
   //
   typedef PVOID HDEVINFO;

From a PB point of view I could just declare this as a LONG or a DWORD, but it isn't always clear what the
DWORD is actually pointing to.

My question is, since PB doesn't support TYPEDEFs, could I replace the simple LONG/DWORD declaration with a
TYPE that contains a LONG/DWORD and thereby gain some code clarity? From the compiler's perspective, are the
two the same or is there extra overhead with the TYPE statement?

   TYPE HDEVINFO
      P AS DWORD
   END TYPE

   LOCAL tHdev as HDEVINFO

   tHdev.P = SomeFunctionThatReturnsOpaquePtr()

   SomeSubThatUsesOpaquePtr(tHdev.P)

In my current project I've got a number of these opaque pointers in use, and while
using descriptive variable names helps, it's still something of a mess.

Thanks!

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Mark Newman