Forum: Ruby what's the purpose of IRB.confand/or TOPLEVEL_BINDING?

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ghorner (Guest)
on 2009-05-22 08:28
(Received via mailing list)
Hi all,
  I'm peering into irb's internals and am wondering what's the purpose
of IRB.conf[:CONTEXT_MODE]? I understand most of the ruby code but all
my googling has yet to bring up _anyone_ who uses this. Here is a link
to the beginning of it's implementation in irb:
http://github.com/akitaonrails/ruby191-stable-mirr...

To summarize the implementation, IRB.conf[:CONTEXT_MODE] can be set to
one of 4 values: 0,1,2,3 (default is 3). Depending on the value, a
binding is created for use when evaluating a line in irb:

0: eval("proc{binding}.call", TOPLEVEL_BINDING ...)
1: creates a binding to a temporary file
2: thread friendly binding from an irb file
3: eval("def irb_binding; binding; end; irb_binding",
TOPLEVEL_BINDING ...)

Right off the bat, I don't know the use cases for cases 1 and 2. Is a
binding in a temporary file perhaps more secure? As for cases 0 and 3
rue on irc helped me understand the difference between them: case 0
the binding has access to local variables of TOPLEVEL_BINDING while
case 3 doesn't. But when I grep in ruby's source, the only mention of
TOPLEVEL_BINDING is in irb libs and erb.rb. So of what use is case 0
when almost no libraries use TOPLEVEL_BINDING and when the binding
could just very well be TOPLEVEL_BINDING itself?

Thoughts, insights?
Thanks,
Gabriel
cldwalker (Guest)
on 2009-05-22 22:21
(Received via mailing list)
On May 21, 2:43 am, ghorner <removed_email_address@domain.invalid> wrote:
> 0: eval("proc{binding}.call", TOPLEVEL_BINDING ...)
> TOPLEVEL_BINDING is in irb libs and erb.rb. So of what use is case 0
> when almost no libraries use TOPLEVEL_BINDING and when the binding
> could just very well be TOPLEVEL_BINDING itself?
>
> Thoughts, insights?
> Thanks,
> Gabriel

I know some of irb's confusing, but is this really that confusing? Any
takers?
Gabriel
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