Questions about embedding Ruby in C

ruby-talk
1

I have some questions regarding how to embed Ruby into C apps:

  1. How can I make Ruby not calling exit() when finished with a script?
    I’ve already seen the variant using rb_set_end_proc(), but is there
    any other way to do it since the program still dies after calling the
    rb_set_end_proc()?

  2. How does it come I can’t see any output from the script I’m
    running? Is it because Ruby decides to run it in a sub-shell or what?

  3. Is it possible to make the interpreter use rubyated C-code from the
    application who called it like an extension library? And if so, how?

Thanks.

-Johan

2

1. How can I make Ruby not calling exit() when finished with a script?

Just don't call ruby_run()

2. How does it come I can't see any output from the script I'm
running? Is it because Ruby decides to run it in a sub-shell or what?

Well, you must give an example to see what you are trying to do.

3. Is it possible to make the interpreter use rubyated C-code from the
application who called it like an extension library? And if so, how?

Look in RAA you have many examples

Guy Decoux

3

Or at least, is there any documentation aviable on the subject?

4

ts decoux@moulon.inra.fr wrote in message news:200211210931.gAL9V5A16309@moulon.inra.fr…

  1. How can I make Ruby not calling exit() when finished with a script?

Just don’t call ruby_run()

  1. How does it come I can’t see any output from the script I’m
    running? Is it because Ruby decides to run it in a sub-shell or what?

Well, you must give an example to see what you are trying to do.

  1. Is it possible to make the interpreter use rubyated C-code from the
    application who called it like an extension library? And if so, how?

Look in RAA you have many examples

Guy Decoux

?

  1. But if I don’t call ruby_run(), how does it interpret?

  2. When I am running a script, say with the line
    puts ‘hello’
    from within my c-program, no ‘hello’ pops up on my term.

  3. What I meaned was like:

    c program:
    VALUE ruby_func()
    {
    /* … */
    }

     void blah_blah()
 {
     ruby_init();
     ruby_script("foo.rb");
     ruby_run();
 }

    foo.rb:
    # …
    ruby_func # call ruby_func that appeared in the
    # … # same app as the caller of ruby_run()

    Is this kind of operation possible?

-Johan

5

Johan Persson wrote:

Or at least, is there any documentation aviable on the subject?

Hi Johan!

I looked through a bunch of examples in the RAA, and here

is what I hacked together, and it seems to work… I’m just a newbie,
so take it all with a grain of salt…
– Glenn

···

=======================================================================

#include <ruby.h>
#include <stdio.h>

static VALUE defout_write(VALUE self, VALUE str)
{
str = rb_obj_as_string(str);
fprintf(stderr, “In defout_write: len=%d, str=‘%s’\n”, RSTRING(str)->len, RSTRING(str)->ptr);
rb_str_cat(self, RSTRING(str)->ptr, RSTRING(str)->len);
return Qnil;
}

static VALUE defout_cancel(VALUE self)
{
fprintf(stderr, “In defout_cancel\n”);
if (RSTRING(self)->len == 0) return Qnil;
RSTRING(self)->len = 0;
RSTRING(self)->ptr[0] = ‘\0’;
return Qnil;
}

static void init()
{
ruby_init();
#if RUBY_VERSION_CODE >= 160
ruby_init_loadpath();
#else
#if RUBY_VERSION_CODE >= 145
rb_ary_push(rb_load_path, rb_str_new2(“.”));
#endif
#endif
rb_defout = rb_str_new(“”, 0);
rb_io_binmode(rb_stdout); /* for mswin32 /
rb_define_singleton_method(rb_defout, “write”, (VALUE()(ANYARGS))&defout_write, 1);
rb_define_singleton_method(rb_defout, “cancel”, (VALUE(*)(ANYARGS))&defout_cancel, 0);
}

static void proc_args(int argc, char **argv)
{
ruby_script(argv[0]);
// Other stuff here for initializing FLTK…
}

int main(int argc, char **argv)
{
// fprintf(stderr, “Calling init…\n”);
init();
// fprintf(stderr, “Calling proc_args…\n”);
proc_args(argc, argv);
// fprintf(stderr, “Calling run…\n”);
Fl::run(); // This is my FLTK GUI… you might not have this,
// but you will need some kind of event loop or something.
// Note that my GUI has callbacks that call ‘ruby_eval’, below…
return 0;
}

VALUE ruby_eval(const char* str)
{
int state = 0;
fprintf(stderr, “Calling ruby: ‘%s’\n”, str);
VALUE val = rb_eval_string_protect(str, &state);
if (state == Qundef) {
fprintf(stderr, “ERROR: Undefined statement: ‘%s’\n”, str);
} else {
fprintf(stderr, “State=%d, return VALUE=%08lX\n”, state, val);
}
return val;
}

6

   Is this kind of operation possible?

Well, this is very quickly written

pigeon% cat a.c
#include <ruby.h>

static VALUE
aa_func(obj)
    VALUE obj;
{
    rb_p(rb_str_new2("I'm is ruby_func"));
    return obj;
}

int main()
{
    ruby_init();
    ruby_init_loadpath();
    rb_define_method(rb_cObject, "ruby_func", aa_func, 0);
    rb_p(rb_str_new2("before b.rb"));
    rb_load_protect(rb_str_new2("b.rb"), Qfalse, 0);
    rb_p(rb_str_new2("after b.rb"));
}
pigeon%

pigeon% cat b.rb
#!/usr/bin/ruby
p "before ruby_func"
ruby_func
p "after ruby_func"
pigeon%

pigeon% a.out
"before b.rb"
"before ruby_func"
"I'm is ruby_func"
"after ruby_func"
"after b.rb"
pigeon%

Guy Decoux

7

“Glenn M. Lewis” glenn@gmlewis.com wrote in message news:3DDD0A19.2060507@gmlewis.com…

Johan Persson wrote:

Or at least, is there any documentation aviable on the subject?

Hi Johan!

I looked through a bunch of examples in the RAA, and here
is what I hacked together, and it seems to work… I’m just a newbie,
so take it all with a grain of salt…
– Glenn

/* code */

I don’t really know if this was what I was looking for, but thanks
anyway! I guess I’ll have to either hack my way through or just wait
till Ruby matures a lil bit before embedding it… :slight_smile:

-Johan