best practise: hiding not defined symbols? [was: problems starting windows compiled help files with start-process]

[Dieter Wilhelm]

Mathias Dahl <brakjoller@gmail.com> writes:

> Dieter Wilhelm <dieter@duenenhof-wilhelm.de> writes:
>
>> I'd like to be able to open a windows (on XP) compiled help file
>> (.chm).  It works well with `shell-process' in just giving the shell
>> the .chm file as argument.  But I can't get it to run with
>> start-process.  Probably I need to call a viewer for this file.  I
>> googled around and found that the internet explorer is supposed to
>> act as "viewer" for these help files.  The next hurdle is where to
>> find the executable, I can't find iexplorer.exe or iexplore.exe on
>> my disk.
>
> Have you tried using `w32-shell-execute'?
>
> (w32-shell-execute "Open" "blabla.chm")
>
> /Mathias

Thanks again, now I've a conditional:

    (cond
     (ansys-is-unix-system
      (start-process "ansys-help" nil ansys-help))
     ((string= system-type "windows-nt")
      (w32-shell-execute "Open" ansys-help)))

This works fine but when trying to byte-compile I get a warning in the
following manner:

w32-shell-execute is not known to be defined under Linux

Can/should I somehow hide the w32-* stuff when compiling under a Unix
system and how?

-- 
    Best wishes

    H. Dieter Wilhelm
    Darmstadt, Germany