Re: Can't use dynamic-link with any shared object file

[Eli Zaretskii]

> Date: Mon, 26 Dec 2016 22:24:21 +0000 (GMT)
> From: Jan Wedekind <address@hidden>
> Cc: address@hidden
> 
> I think "libc" is normally loaded already. E.g. the C function "abs" can 
> be accessed as follows:
> 
>      (define main (dynamic-link))
>      (define cabs (pointer->procedure long (dynamic-func "abs" main) (list 
> long)))
>      (cabs -42)
>      ; 42

This is non-portable, and doesn't work outside of the Posix world.
E.g., on MS-Windows (with Guile 2.0.x):

  D:\usr\eli\data>guile
  GNU Guile 2.0.11
  Copyright (C) 1995-2014 Free Software Foundation, Inc.

  Guile comes with ABSOLUTELY NO WARRANTY; for details type `,show w'.
  This program is free software, and you are welcome to redistribute it
  under certain conditions; type `,show c' for details.

  Enter `,help' for help.
  scheme@(guile-user)> ,use (system foreign)
  scheme@(guile-user)> ,use (rnrs bytevectors)
  scheme@(guile-user)> (define main (dynamic-link))
  scheme@(guile-user)> (define cabs (pointer->procedure long (dynamic-func 
"abs" main) (list long)))
  ERROR: In procedure dynamic-func:
  ERROR: In procedure dynamic-pointer: Symbol not found: abs

  Entering a new prompt.  Type `,bt' for a backtrace or `,q' to continue.
  scheme@(guile-user) [1]> ,q

But (msvcrt.dll is the C runtime library on Windows):

  scheme@(guile-user)> (define libc (dynamic-link "msvcrt.dll"))
  scheme@(guile-user)> (define cabs (pointer->procedure long (dynamic-func 
"abs" libc) (list long)))
  scheme@(guile-user)> (cabs -42)
  $1 = 42
  scheme@(guile-user)>