[M3devel] Constant to Constant?

[Coleburn, Randy]

Chris:

You may also want to look at pkg\m3core\src\win32\WinUser.i3

Regards,
Randy

-----Original Message-----
From: Chris [mailto:Highjinks at gmx.com]
Sent: Thursday, March 11, 2010 7:35 PM
To: m3devel at elegosoft.com
Subject: [M3devel] Constant to Constant?


Things are progressing here, slowly but steadily.

I'm curious...

When writing an interface for something like this ...

/* C Type */
const C_Foo_t  *Bar = get_foo_data(misc);

Is it better to do it this way...

<* EXTERNAL get_foo_data:C *>
TYPE Foo_Data = PROCEDURE(get_foo_data(somemisc : misctype) : C_Foo_t;

Or should I just do...
UNSAFE INTERFACE Foo;

(* Translating the C typedef struct over to Modula3 code. *)
TYPE C_Foo_T = UNTRACED REF RECORD .... END;

<* EXTERNAL get_foo_data:C *>
PROCEDURE get_foo_data(somemisc : misctype) : C_foo_t;
END Foo.

Main.m3
IMPORT Foo;
Foo_Data := Foo.get_foo_data(Misc);
END Main.

C_Foo_t is known, and has a Modula 3 representation in the Interface. But as the C Code shows, it has to be a constant value.

What's the best way to do this without hosing the Interface for everyone else that might want to use it? Variable expressions are no problem, it's making it a constant that's giving me trouble. It's constant because the data structure is managed by the supporting library, not by the Modula3 Code.

Tips...pointers?

--
Chris <Highjinks at gmx.com>

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