From: ruby-core@...
Date: 2014-05-02T02:43:47+00:00
Subject: [ruby-core:62275] [ruby-trunk - Feature #9781] Feature Proposal:	Method#super_method

Issue #9781 has been updated by Marc-Andre Lafortune.


Hi,

Ryan Davis wrote:
> Maybe it is just me misunderstanding something... but this doesn't seem that complicated. I don't understand why you'd walk through the ancestors when you just just ask one level up:

For one level, with simple class inheritance, it probably isn't, but throw in a prepended module or two, and the desire to go up more than one level (i.e. `obj.method(:foo).super_method.super_method`) and it's not completely trivial.

If ever we support a module being included more than once in the ancestry chain, then it's actually impossible (unless Method provides a more extensive api to tell where it is in the ancestry chain).

I'm +1 for this feature, although I would favor the shorter name `super`. I don't think it would ever conflict with the keyword, and if it did there is still the same solution as with `class`, i.e. `self.super`.

----------------------------------------
Feature #9781: Feature Proposal: Method#super_method
https://bugs.ruby-lang.org/issues/9781#change-46439

* Author: Richard Schneeman
* Status: Open
* Priority: Normal
* Assignee: 
* Category: core
* Target version: 
----------------------------------------

When `super` is called in a method the Ruby VM knows how to find the next ancestor that has that method and call it. It is difficult to do this manually, so I propose we expose this information in Method#super_location.

Ruby Method class (http://www.ruby-doc.org/core-2.1.1/Method.html) is returned by calling Object.method and passing in a method name (http://www.ruby-doc.org/core-2.1.1/Object.html#method-i-method). This is useful for debugging:

```ruby
# /tmp/code.rb
class Foo
  def bar
  end
end

puts Foo.new.method(:bar).source_location
# => ["/tmp/code.rb", 3]
```

The Object#method allows a ruby developer to easily track the source location of the method and makes debugging very easy. However if the code is being invoked by a call to `super` it is difficult to track down:

```ruby
# /tmp/code.rb

class BigFoo
  def bar
  end
end

class Foo < BigFoo
  def bar
    super
  end
end
```

In this code sample it is easy to find the method definition inside of Foo but it is very difficult in large projects to find what code exactly `super` is calling. This simple example is easy, but it can be hard when there are many ancestors. Currently if I wanted to find this we can inspect ancestors

```ruby
Foo.ancestors[1..-1].map do |ancestor|
  next unless ancestor.method_defined?(:bar)
  ancestor.instance_method(:bar)
end.compact.first.source_location
```

To make this process simpler I am proposing a method on the Method class that would return the result of `super`


It could be called like this:

```ruby
Foo.new.method(:bar).super_method
```

I believe adding Method#super_method, or exposing this same information somewhere else, could greatly help developers to debug large systems easily.




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