From: alex.wayfer@...
Date: 2018-11-15T10:02:27+00:00
Subject: [ruby-core:89807] [CommonRuby Feature#13581] Syntax sugar for	method reference

Issue #13581 has been updated by AlexWayfer (Alexander Popov).


zverok (Victor Shepelev) wrote:
> @nobu
> 
> > If `.:` will be introduced, I think it should obey that syntax too, and allowing it without the receiver feels confusing.
> 
> Can you please show some example of confusing statements? I can't think of any from the top of my head, it seems that (if the parser can handle it), the context for `.:something` and `.something` is always clearly different.
> 
> I am concerned about receiver-less version because in our current codebase we found this idiom to be particularly useful:
> 
> ```ruby
> # in a large data-processing class
> some_input
>   .compact
>   .map(&method(:process_item)) # it is private method of current class
>   .reject(&method(:spoiled?))
>   .tap(&method(:pp)) # temp debugging statement
>   .group_by(&method(:grouping_criterion))
>   .yield_self(&method(:postprocess))
> 
> # which I'd be really happy to see as
> some_input
>   .compact
>   .map(&.:process_item)
>   .reject(&.:spoiled?)
>   .tap(&.:pp)
>   .group_by(&.:grouping_criterion)
>   .then(&.:postprocess)
> 
> ```
> Having to explicitly state `map(&self.:process_item)` is much less desirable.

Just an opinion:

```ruby
processed =
  some_input
    .compact
    .map { |element| ProcessingItem.new(element) } # or `.map(&ProcessingItem.method(:new))`
    .reject(&:spoiled?)
    .each(&:pp) # temp debugging statement
    .group_by(&:grouping_criterion)

postprocess processed
```

Or you can even use `ProcessingItems` collection class. With itself state and behavior. Instead of bunch of private methods in a processing class with the same (collection) argument.

----------------------------------------
Feature #13581: Syntax sugar for method reference
https://bugs.ruby-lang.org/issues/13581#change-74869

* Author: americodls (Americo Duarte)
* Status: Open
* Priority: Normal
* Assignee: 
* Target version: 
----------------------------------------
Some another programming languages (even Java, in version 8) has a cool way to refer a method as a reference.

I wrote some examples here: https://gist.github.com/americodls/20981b2864d166eee8d231904303f24b

I miss this thing in ruby.

I would thinking if is possible some like this:

~~~
roots = [1, 4, 9].map &Math.method(:sqrt)
~~~

Could be like this:

~~~
roots = [1, 4, 9].map Math->method
~~~

What do you guys thinking about it?



-- 
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>