From: Robert Feldt <feldt@...>
Date: 2001-03-06T19:24:09+09:00
Subject: [ruby-talk:12111] Re: RCR: replacing 'caller'

On Tue, 6 Mar 2001, Avi Bryant wrote:

> Nice... this is, of course, exactly what we needed to be able to play with
> dispatchers in pure ruby.
>   
> However, it needs some error checking:
> 
> class Foo
> 	define_method(:x) {puts call_stack[0]}
> end
> 
> Foo.new.x #=> SEGFAULT
> 
> I can work around it for new by using call_stack(2)...
> 
Problem is that last_func is 0 when block called. New diff (from original
in latest snapshot) that should work better is below. However, I return
nil instead of a method when a block. Maybe should return the block
instead? Dunno...

/Robert



--- eval.c.orig	Tue Mar  6 06:00:04 2001
+++ eval.c	Tue Mar  6 11:16:36 2001
@@ -4687,6 +4687,58 @@
 }
 
 static VALUE
+call_stack(lev)
+    int lev;
+{
+    struct FRAME *frame = ruby_frame;
+    VALUE ary = rb_ary_new();
+    VALUE inner_ary;
+
+    while (lev-- > 0) {
+      frame = frame->prev;
+      if (!frame) {
+	ary = Qnil;
+	break;
+      }
+    }
+    while (frame && frame->file) {
+      inner_ary = rb_ary_new();
+      rb_ary_push(inner_ary, frame->self);
+      if(frame->last_func == 0)
+	rb_ary_push(inner_ary, Qnil);
+      else {
+	rb_ary_push(inner_ary, ID2SYM(frame->last_func));
+      }
+      rb_ary_push(inner_ary, rb_ary_new4(frame->argc, frame->argv));
+      rb_ary_push(inner_ary, rb_str_new2(frame->file));
+      rb_ary_push(inner_ary, INT2FIX(frame->line));
+      // Add block if block_given? ie. check iter stack and traverse
block
+      // stack accordingly...
+      rb_ary_push(ary, inner_ary);
+      frame = frame->prev;
+    }
+
+    return ary;
+}
+
+static VALUE
+rb_f_call_stack(argc, argv)
+    int argc;
+    VALUE *argv;
+{
+    VALUE level;
+    int lev;
+
+    rb_scan_args(argc, argv, "01", &level);
+
+    if (NIL_P(level)) lev = 1;
+    else lev = NUM2INT(level);
+    if (lev < 0) rb_raise(rb_eArgError, "negative level(%d)", lev);
+
+    return call_stack(lev);
+}
+
+static VALUE
 rb_f_caller(argc, argv)
     int argc;
     VALUE *argv;
@@ -5869,6 +5921,7 @@
     rb_define_global_function("fail", rb_f_raise, -1);
 
     rb_define_global_function("caller", rb_f_caller, -1);
+    rb_define_global_function("call_stack", rb_f_call_stack, -1);
 
     rb_define_global_function("exit", rb_f_exit, -1);
     rb_define_global_function("abort", rb_f_abort, 0);