[gambit-list] runtime settings

Marc Feeley feeley at iro.umontreal.ca
Thu Jul 27 23:49:58 EDT 2006

On 27-Jul-06, at 5:04 PM, Ryan Prescott wrote:

> What is the proper way to set runtime settings for a compiled  
> scheme program?
> Does an executable compiled with:
> gsc -:tl myfile.scm
> "inherit" the -:tl setting?

No it doesn't.  However, if you write your program as a script, that  
is it starts with a line with "#! gsi ..." (on Unix) or "@;  
gsi ..." (on Windows) then the compiled program will set the same  
runtime options as the one specified to the script interpreter,  
unless it is overridden with an explicit "-:..." options when the  
program is started.  Note that the script interpreter will not be  
executed by the compiled program, the first line is only parsed by  
the compiler to get the default runtime options.

Here's a detailed example.  Let's say you want the program to use CR- 
LF as the end-of-line encoding for all file I/O by default.  You  
would write "myfile.scm" as a script like this (on Unix):

#! gsi-script -:fcl
(define (main)
   (display "hello\n"))

then you would compile and execute it like this:

% gsc myfile.scm
% gcc myfile.c myfile_.c -lgambc -lm -ldl -lutil
% ./a.out  | od -a
0000000   h   e   l   l   o  cr  nl

The nice thing about this way of getting the default runtime options  
is that you get the same result as executing the script:

% chmod +x myfile.scm
% ./myfile.scm  | od -a
0000000   h   e   l   l   o  cr  nl

Yet another approach is to set the GAMBCOPT environment variable:

% export GAMBCOPT=tcl

Gambit compiled programs executed after this will use the default  
runtime options "-:tcl" (these can be overridden on the program  
command line).

> Likewise for c initiated scheme apps? by setting the setup struct's  
> members?

Yes you can do that, for example:

#define MY_LINKER ____20_myprog__

extern ___mod_or_lnk MY_LINKER (___global_state_struct*);

void setup_gambit ()
   ___setup_params_struct setup_params;

   ___setup_params_reset (&setup_params);

   setup_params.version = ___VERSION;
   setup_params.linker  = MY_LINKER;

   /* set UTF-8 character encoding for file I/O */

   setup_params.file_settings = ___FILE_SETTINGS_INITIAL;
   setup_params.file_settings = ___CHAR_ENCODING_MASK 

   ___setup (&setup_params);


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