From: 2851820660@qq.com
To: ruby-core@ruby-lang.org
Subject: [ruby-core:69905] [CommonRuby - Feature #7747] Expanded API for Binding semantics
Date: Thu, 09 Jul 2015 05:10:15 +0000 [thread overview]
Message-ID: <redmine.journal-53324.20150709051014.1ee9a50b07d08842@ruby-lang.org> (raw)
In-Reply-To: redmine.issue-7747.20130128080812@ruby-lang.org
Issue #7747 has been updated by 11 22.
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Feature #7747: Expanded API for Binding semantics
https://bugs.ruby-lang.org/issues/7747#change-53324
* Author: Joshua Ballanco
* Status: Open
* Priority: Normal
* Assignee:
----------------------------------------
=begin
Currently, the only way to create a new instance of Binding is to get a copy of the current scope's binding, or ask some other object for its binding. In either case, the binding object returned always has semantics identical to the original binding. In other words, a binding object used with eval is capable of (not necessarily an exhaustive list):
* redefining methods on the binding target
* defining new methods on the binding target
* getting/setting instance variables
* getting/creating new constants
This feature proposal would introduce a new mechanism for creating a binding and adjusting its relationship with the source binding. For example, if you have a class (({Foo})) defined like so:
class Foo
def say
puts "hello!"
end
end
Then you would be able to create a new binding that ((*won't*)) propagate new definitions to the parent binding like so:
new_binding = Binding.new(Foo)
new_binding.propagate = false
new_binding.eval("def shout; puts 'HI!'; end")
Foo.new.say #=> "hello!"
Foo.new.shout #=> No Method Error
new_binding.eval("Foo.new.say") #=> "hello"
new_binding.eval("Foo.new.shout") #=> "HI!"
If, additionally, we introduce a way to merge or combine bindings, then this API could actually be used to implement refinements in pure Ruby like so (note I am also assuming that (({Binding#eval})) gains the ability to take a block):
class Module
def refine(klass, &block)
@refined_bindings ||= {}
refinement_binding = Binding.new(klass)
refinement_binding.propagate = false
refinement_binding.shadow = true
refinement_binding.eval &block
(@refined_bindings[self.name] ||= []) << refinement_binding
end
def using(mod)
@refined_bindings[mod].each { |refinement| self.binding.merge(refinement) }
end
end
Following is the preliminary list of additional APIs I am tentatively proposing (though I expect this to change with additional discussion):
* (({Binding.new(an_object)})) - creates a new Binding object that "inherits" the binding of the argument; essentially equivalent to (({an_object.send(:binding).dup}))
* (({Binding#propagate}))/(({Binding#propagate=})) - boolean; determines whether new method, class, or Constant defs are propagated into the "parent" binding's scope
* (({Binding#shadow}))/(({Binding#shadow=})) - boolean; sets whether or not new values for existing methods/constants/variables can be set
* (({Binding#freeze})) - causes the Binding to capture all existing methods/constants/variables in scope at call time, and "disconnect" from the parent binding, so that any updates to definitions or values are no longer reflected into the "child" binding
* (({Binding#merge(other_binding)})) - combines the method/constant/variable bindings in (({other_binding})) with the receiver; effectively shadows the "parent" of (({other_binding})) within the receiver binding
=end
--
https://bugs.ruby-lang.org/
prev parent reply other threads:[~2015-07-09 4:43 UTC|newest]
Thread overview: 18+ messages / expand[flat|nested] mbox.gz Atom feed top
2013-01-27 23:09 [ruby-core:51714] [CommonRuby - Feature #7747][Open] Expanded API for Binding semantics jballanc (Joshua Ballanco)
2013-01-27 23:18 ` [ruby-core:51716] [CommonRuby - Feature #7747] " jballanc (Joshua Ballanco)
2013-03-07 22:48 ` [ruby-core:53201] " pasvan (paster okan)
2013-09-23 5:05 ` [ruby-core:57312] " pasvan (paster okan)
2014-03-12 13:52 ` [ruby-core:61436] " bookingfirm
2014-05-12 18:41 ` [ruby-core:62549] " yesilkahvezayiflama
2014-05-12 23:35 ` [ruby-core:62550] " nobu
2014-05-13 0:15 ` [ruby-core:62551] " nobu
2014-11-10 11:15 ` [ruby-core:66170] " sertackaya
2014-11-22 17:13 ` [ruby-core:66417] " sertackaya
2014-11-22 20:45 ` [ruby-core:66418] " sertackaya
2014-11-23 11:21 ` [ruby-core:66426] " sertackaya
2014-11-23 11:21 ` [ruby-core:66427] " sertackaya
2015-01-18 8:09 ` [ruby-core:67674] " sertackaya
2015-01-18 19:48 ` [ruby-core:67677] " fatblockshop
2015-02-25 9:15 ` [ruby-core:68305] " sertackaya
2015-07-09 5:09 ` [ruby-core:69904] " 2851820660
2015-07-09 5:10 ` 2851820660 [this message]
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