Re: What about Object#to_ruby ?

Thanks a lot for your responses. I suspect that my question was not that
clear, though.

I'm not really looking or Marshal or YAML or JSON dump format, but for a
method
to print a ruby *literal* (I should have called it to_ruby_literal) from a
ruby value,
where it makes sense. The goal is to ease human-readable ruby code
generation,
I must add. Nowadays, using inspect works for all but a few basic values:

blambeau@kali:~$ irb -r time to_ruby_literal.rb
ruby-1.8.7-p334 :001 > eval(true.inspect)
 => true
ruby-1.8.7-p334 :002 > eval(1.inspect)
 => 1
ruby-1.8.7-p334 :003 > eval(1.0.inspect)
 => 1.0
ruby-1.8.7-p334 :004 > eval(nil.inspect)
 => nil
ruby-1.8.7-p334 :005 > eval("O'Neil".inspect)
 => "O'Neil"
ruby-1.8.7-p334 :006 > eval('O " Dude'.inspect)
 => "O \" Dude"
ruby-1.8.7-p334 :007 > eval([1, 2, 3].inspect)
 => [1, 2, 3]
ruby-1.8.7-p334 :008 > eval({:hello => "world"}.inspect)
 => {:hello=>"world"}
ruby-1.8.7-p334 :009 > eval(/[a-z]*/.inspect)
 => /[a-z]*/
ruby-1.8.7-p334 :010 > eval((1.0/0).inspect)
NameError: (eval):1:in `irb_binding': uninitialized constant Infinity
from to_ruby_literal.rb:10
from to_ruby_literal.rb:10
ruby-1.8.7-p334 :011 > eval(Time.now.inspect)
SyntaxError: (eval):1:in `irb_binding': compile error
(eval):1: syntax error, unexpected tINTEGER, expecting $end
Mon Jun 20 20:01:19 +0200 2011
             ^
from to_ruby_literal.rb:11
from to_ruby_literal.rb:11

Bernard

On Mon, Jun 20, 2011 at 7:37 PM, Josh Cheek <[e-mail]> wrote:

> On Mon, Jun 20, 2011 at 7:40 AM, Bernard Lambeau <[e-mail]>
> wrote:
>
> > Hi!
> >
> > It's not the first time that I need a to_ruby method which would
> guarantee
> > the following invariant:
> >
> >  Kernel.eval(foo.to_ruby) == foo
> >
> > It actually works when using inspect with most basic objects (Integer,
> > String,
> > True & FalseClass, etc.), without actually being the specification of
> > inspect.
> >
> > I admit that such a feature probably only makes sense for classes that
> > actually
> > capture datatypes, whose instances are then true values.
> >
> > Does anyone know a gem that provides such a feature? To your knowledge,
> > would to_ruby be a conflicting name with existing gems in the ecosystem
> > or future plans for ruby itself?
> >
> > Just in case you ask yourself whether this feature is needed, have a look
> > at rubygems itself:
> >
> >
> https://github.com/rubygems/rubygems/blob/master/lib/rubygems/specification.rb#L1899-1915
> >
> > Thanks for any suggestion,
> > Bernard
> >
> > --
> > PhD Student, Computer Science Department, EPL/INGI, UCLouvain, Belgium
> > Mail:    [e-mail]
> > Mobile:  [phone]
> > Blog:    http://revision-zero.org/
> > Code:    http://github.com/blambeau/
> > Follow:  http://twitter.com/blambeau/
> >
>
> # I think the following works for everything except data that contains code
> itself (closures / methods)
>
> Datum = Struct.new :some_attribute
>
> data = [
>  Datum.new("string"),
>  Datum.new(1234),
>  Datum.new(/regex/),
> ]
>
>
> serial = Marshal.dump data
> serial                        # =>
>
> "\x04\b[\bS:\nDatum\x06:\x13some_attributeI\"\vstring\x06:\x06ETS;\x00\x06;\x06i\x02\xD2\x04S;\x00\x06;\x06I/\nregex\x00\x06;\aF"
> Marshal.load(serial) == data  # => true
>
> require 'yaml'
> serial = YAML.dump data
> serial                        # => "--- \n- !ruby/struct:Datum \n
>  some_attribute: string\n- !ruby/struct:Datum \n  some_attribute: 1234\n-
> !ruby/struct:Datum \n  some_attribute: !ruby/regexp /regex/\n"
> YAML.load(serial) == data     # => true
>
> ---
>
> I think the closest things that exist right now that would be able to do
> this for closures as well, would be some of Ryan Davis' tools (last I
> heard,
> they don't work on 1.9, though):
> https://rubygems.org/gems/ruby2ruby
> https://rubygems.org/gems/ruby_parser
> https://rubygems.org/gems/sexp_processor
>
> Rubinius might also be able to do something like this.
>
>
> On Mon, Jun 20, 2011 at 12:20 PM, Steve Klabnik <[e-mail]
> >wrote:
>
> > I believe pry has this kind of thing: https://github.com/banister/pry
> >
> > From its readme:
> >
> > pry(Pry):1> show-method rep -l
> >
> > From: /home/john/ruby/projects/pry/lib/pry/pry_instance.rb @ line 143:
> > Number of lines: 6
> >
> > 143: def rep(target=TOPLEVEL_BINDING)
> > 144:   target = Pry.binding_for(target)
> > 145:   result = re(target)
> > 146:
> > 147:   show_result(result) if should_print?
> > 148: end
> >
>
> I'm admittedly uninformed, but I think they do this by keeping track of
> where methods get defined, then opening that file and reading that
> definition (as opposed to introspecting on the object itself) in the
> example
> above, for instance, they also report the file and line numbers of the rep
> method.
>



-- 
PhD Student, Computer Science Department, EPL/INGI, UCLouvain, Belgium
Mail:    [e-mail]
Mobile:  [phone]
Blog:    http://revision-zero.org/
Code:    http://github.com/blambeau/
Follow:  http://twitter.com/blambeau/