# Why is the Binding object so useless?
**URL:** https://rubytalk.org/t/why-is-the-binding-object-so-useless/57135
**Category:** ruby-talk
**Created:** [25 January 2010 20:56 UTC](https://rubytalk.org/t/why-is-the-binding-object-so-useless/57135 "2010-01-25T20:56:44Z")
**Posts on this page:** 4
**Page:** 1
### Author:  [@Tony\_Arcieri6](https://rubytalk.org/u/Tony_Arcieri6)
#### Post date: [25 January 2010 20:56 UTC](https://rubytalk.org/t/why-is-the-binding-object-so-useless/57135/1 "2010-01-25T20:56:44Z")
I am used to Ruby being a rather reflective language that gives carte
blanche to the programmer. So I found this rather surprising:
> > Marshal.dump binding
TypeError: no marshal\_dump is defined for class Binding
Whaa?
> > Binding.new
NoMethodError: undefined method `new' for Binding:Class
Huh?
> > binding.methods(false)
=\>
You're kidding me, right?
I would expect you to be able to do all of the above. In addition to that,
it's sure be nice to do some of the following:
> > Binding.new :a =\> 1, :b =\> 2, :c =\>3
=\> #\ # new binding object with the given variables
bound
> > binding.to\_hash
=\> {:a =\> 1, :b =\> 2, :c =\> 3} # Bound variables, as a hash
> > binding.to\_yaml
=\> "--- !ruby/object:Binding \na: 1\nb: 2\nc: 3\n" # YAML dump of a Binding
object
And hey, maybe Binding#inspect could give a little more information than its
object\_id?
Canned responses to apologists:
= Why do you want to do that?
I don't know, why should you be able to redefine Integer#+?
= No really, why do you want to do that?
I would like to implement a remote REPL with a stateless Ruby server and a
non-Ruby client
= Just use DRb!
I am really not wanting to open up an addition port just for DRb nor pursue
solutions which involve a non-Ruby client talking the DRb protocol.
Embedding some form of Ruby interpreter client side is not an option.
Props to Rubinius for fixing some of these problems!
irb(main):001:0\> Binding.new
=\> #\
Yay! A clean binding!
> > Marshal.dump Binding.new
=\> "\004\bo:\fBinding\000"
Amazing!
> **···**
>
> --
> Tony Arcieri
> Medioh! A Kudelski Brand
---
### Author:  [@Brian\_Candler](https://rubytalk.org/u/Brian_Candler)
#### Post date: [26 January 2010 14:40 UTC](https://rubytalk.org/t/why-is-the-binding-object-so-useless/57135/2 "2010-01-26T14:40:34Z")
Tony Arcieri wrote:
> = No really, why do you want to do that?
>
> I would like to implement a remote REPL with a stateless Ruby server and
> a
> non-Ruby client
Your proposed feature would also make things like the ActionPack
template rendering much cleaner. grep for "local\_assigns" in
action\_view/renderable.rb (rails 2.3.x) and weep. Here is what they end
up doing, where local\_assigns is a hash of variable=\>value bindings:
def compile!(render\_symbol, local\_assigns)
locals\_code = local\_assigns.keys.map { |key| "#{key} =
local\_assigns[:#{key}];" }.join
source = \<\<-end\_src
def #{render\_symbol}(local\_assigns)
old\_output\_buffer =
output\_buffer;#{locals\_code};#{compiled\_source}
ensure
self.output\_buffer = old\_output\_buffer
end
end\_src
(Rails 3 is the same, but the file is action\_view/template.rb and the
method is compile not compile!)
The above is probably what your REPL server should do.
I guess what you propose wasn't implemented simply because it involves
work to convert bindings between their internal representation and
external forms like Hash and Marshal#dump. If you grab an existing live
binding and pass it around, the conversion isn't required.
> **···**
>
> --
> Posted via [http://www.ruby-forum.com/\](http://www.ruby-forum.com/%5C).
---
### Author:  [@Robert\_K1](https://rubytalk.org/u/Robert_K1)
#### Post date: [26 January 2010 15:07 UTC](https://rubytalk.org/t/why-is-the-binding-object-so-useless/57135/3 "2010-01-26T15:07:48Z")
> I am used to Ruby being a rather reflective language that gives carte
> blanche to the programmer. So I found this rather surprising:
>
> > > Marshal.dump binding
>
> TypeError: no marshal\_dump is defined for class Binding
>
> Whaa?
I don't think it does make sense to serialize a binding for the same
reason that you cannot create a new binding: a binding is bound to a
particular program context - I assume this also includes caller stack
and other internal state.
Even if a binding contains local variables what is the effect of
deserializing a binding? If your local variables get updated that is
certainly not a good idea. If you want to serialize state use objects
with the proper state.
> > > Binding.new
>
> NoMethodError: undefined method `new' for Binding:Class
>
> Huh?
A binding is not a regular object but it is a handle on the state of
the runtime. A method object cannot be serialized as well because
that would mean that the original code would have to be written (and
read); this also has security implications (in the case of Method).
But if you have to\_hash you can serialize that.
> I would expect you to be able to do all of the above. In addition to that,
> it's sure be nice to do some of the following:
>
> > > Binding.new :a =\> 1, :b =\> 2, :c =\>3
>
> =\> #\ # new binding object with the given variables
> bound
As above.
> > > binding.to\_hash
>
> =\> {:a =\> 1, :b =\> 2, :c =\> 3} # Bound variables, as a hash
>
> > > binding.to\_yaml
>
> =\> "--- !ruby/object:Binding \na: 1\nb: 2\nc: 3\n" # YAML dump of a Binding
> object
Same as above for Marshal.
> And hey, maybe Binding#inspect could give a little more information than its
> object\_id?
Yeah, #to\_hash and #inspect sound pretty good. You might even add a
method #update receiving a Hash which is interpreted as a mapping from
local variables to values and which overwrites the current binding.
Kind regards
robert
> **···**
>
> 2010/1/25 Tony Arcieri \:
>
> --
> remember.guy do |as, often| as.you\_can - without end
> [http://blog.rubybestpractices.com/](http://blog.rubybestpractices.com/)
---
### Author:  [@Tony\_Arcieri6](https://rubytalk.org/u/Tony_Arcieri6)
#### Post date: [26 January 2010 19:07 UTC](https://rubytalk.org/t/why-is-the-binding-object-so-useless/57135/4 "2010-01-26T19:07:28Z")
> \> I am used to Ruby being a rather reflective language that gives carte
> \> blanche to the programmer. So I found this rather surprising:
> \>
> \>\>\> Marshal.dump binding
> \> TypeError: no marshal\_dump is defined for class Binding
> \>
> \> Whaa?
>
> I don't think it does make sense to serialize a binding for the same
> reason that you cannot create a new binding: a binding is bound to a
> particular program context - I assume this also includes caller stack
> and other internal state.
Why can't bindings be independently garbage collected objects too? (as it
appears they are in rbx)
> Even if a binding contains local variables what is the effect of
> deserializing a binding? If your local variables get updated that is
> certainly not a good idea. If you want to serialize state use objects
> with the proper state.
The goal is to have an object to pass to eval as the binding argument, not
to update locals.
Ideally I could pass a fresh binding (made with Binding.new) to eval, and
when eval is finished it will be updated with whatever assignments were made
in the evaluated code. I could then serialize this and persist it until the
next eval call.
> **···**
>
> On Tue, Jan 26, 2010 at 8:07 AM, Robert Klemme \wrote:
>
> > 2010/1/25 Tony Arcieri \:
>
> --
> Tony Arcieri
> Medioh! A Kudelski Brand