From: merch-redmine@...
Date: 2019-07-11T02:33:39+00:00
Subject: [ruby-core:93657] [Ruby master Bug#10006] instance_exec uses incorrect binding with curried proc

Issue #10006 has been updated by jeremyevans0 (Jeremy Evans).


I think the current behavior is the behavior that should be expected.  It mirrors the behavior you would expect if you implemented `Proc#curry` in Ruby:

```ruby 
class Test
  def test_func
    140
  end
end  # => :test_func

p = ->(x, y) { x + y + test_func }
curried = ->(y) { p.call(1, y) }
test.instance_exec(2, &curried)
```

Changing `Proc#curry` to internally use `instance_exec` for curried procs would fix this case and break the opposite case:

```ruby
class Test
  def test_func
    140
  end

  def p
    ->(x, y) { x + y + test_func }
  end
end

# Current behavior: works
curried = Test.new.p.curry[1]

# Proposed behavior using instance_exec: breaks
#curried = ->(y) { instance_exec(1, y, &Test.new.p) }

instance_exec(2, &curried)
```

That being said, there is a valid argument that `instance_exec(arg, &proc)` and `instance_exec(&proc.curry[arg])` should operate the same way, just as `proc.call(arg)` and `proc.curry[arg].call` operate the same way.

----------------------------------------
Bug #10006: instance_exec uses incorrect binding with curried proc
https://bugs.ruby-lang.org/issues/10006#change-79267

* Author: ledbettj (John Ledbetter)
* Status: Open
* Priority: Normal
* Assignee: 
* Target version: 
* ruby -v: ruby 2.2.0dev (2014-07-02 trunk 46660) [x86_64-darwin13]
* Backport: 2.0.0: UNKNOWN, 2.1: UNKNOWN
----------------------------------------
After using `Proc#curry`, `instanve_eval`/`instance_exec` does not seem to work:

~~~ruby
class Test
  def test_func
    140
  end
end  # => :test_func

p = ->(x, y) { x + y + test_func }  # => #<Proc:0x007fd23b12bc80@(irb):6 (lambda)>

test = Test.new                     # => #<Test:0x007fd23b0f3d08>
test.instance_exec(1, 2, &p)        # => 143

curried = p.curry[1]                # => #<Proc:0x007fb3142be070 (lambda)>
test.instance_exec(2, &curried)
~~~
~~~
NameError: undefined local variable or method `test_func' for main:Object
	from (irb):6:in `block in irb_binding'
	from (irb):10:in `instance_exec'
	from (irb):10
	from ./bin/irb:11:in `<main>'
~~~



-- 
https://bugs.ruby-lang.org/

Unsubscribe: <mailto:ruby-core-request@ruby-lang.org?subject=unsubscribe>
<http://lists.ruby-lang.org/cgi-bin/mailman/options/ruby-core>