Toplevel_object

Ruby
1

This is a Ruby Change Request.
http://rcrchive.net/rcrs/19

Ruby lacks a TOPLEVEL_OBJECT constant, which provides access to the
object resulting from this Ruby expression:

eval( ‘self’, ::TOPLEVEL_BINDING )

That object is a built-in object of the Ruby programming language,
which should be accessible from any point in Ruby code. It is
well-suited to be assigned to a constant. This constant assignment is
comparable to TOPLEVEL_BINDING, in that, while any library could
assign the value to a constant, it is an object inherent to the Ruby
programming language, and therefore should be assigned to a constant
by the core library.

Specifically, a use case where I found the need to assign
TOPLEVEL_OBJECT was in a tracing program, where it was helpful to
exclude certain objects from being traced. TOPLEVEL_OBJECT needed to
be referenced to be added to the list of exclusions. As previously
stated, it can be trivially assigned to TOPLEVEL_OBJECT, or found
dynamically via it’s definition above, it should be included in the
Ruby core, and it is inappropriate for any other library to assign it.

Daniel Brumbaugh K.

2

On Mar 26, 5:28 am, “Daniel Brumbaugh K.”
[email protected] wrote:

comparable to TOPLEVEL_BINDING, in that, while any library could
Ruby core, and it is inappropriate for any other library to assign it.
+1

I also would like to ask why Ruby calls this object “main”, but does
not use it in any other way.

$ irb

self
=> main

T.

3

Hi,

On Wed, Mar 26, 2008 at 10:41 PM, Trans [email protected] wrote:

I also would like to ask why Ruby calls this object “main”, but does
not use it in any other way.

Found it!

static VALUE
main_to_s(VALUE obj)
{
return rb_str_new2(“main”);
}

I jest, of course. :slight_smile: We also see it actually declared/defined this way:

void
Init_top_self()
{
rb_vm_t *vm = GET_VM();

vm->top_self = rb_obj_alloc(rb_cObject);
rb_define_singleton_method(rb_vm_top_self(), "to_s", main_to_s, 0);

}

I guess, it needs to be called something - or should be called
something,
just to distinguish it! So here’s a way.

Cheers,
Arlen