[ruby-core:91047] [Ruby trunk Feature#15526] New way to destruct an object hash

[janfri26@gmail.com]

Issue #15526 has been updated by janfri (Jan Friedrich).


zverok (Victor Shepelev) wrote:
> 1) Ruby has very consistent "argument **deconstruction**" rules. Basically, "it is deconstructed the same way it is constructed", e.g., if you can _call_ (construct) with arguments like `meth(a, *b, c: 1, d: 2, **e)`, you can also _receive_ (deconstruct) arguments exactly the same way: `a, *b, c:, d: nil, **e`.
> 
> 2) The deconstruction is fully enabled in arguments (including keyword arguments) to procs and methods
> 
> 3) Initially (before keyword arguments), the variable assignment had the same "expressive power", e.g. you could define a method like 
> 
> ```ruby
> def meth(a, b, *rest)
> ```
> ...and you could assign variables the same way:
> 
> ```ruby
> a, b, *rest = [1, 2, 3, 4]
> ```
> 
> 4) When keyword arguments were introduced, there was no matching syntax for variable assignment. If it **would** exist, it most probably **should** look this way (same as arguments, remember):
> 
> ```ruby
> a:, b:, **kwrest = {a: 1, b: 2, c: 3, d: 4}
> ```
> It obviously looks confusing (and would probably be hard for the parser), and I believe that's the reason it was NOT added to the language.
> 
> 5) I don't think adding "orphan feature" (looking like nothing else in the language) just for the sake of this particular case would be ever accepted; and I don't think it should.
> 
> 6) In the meantime, "chainable" code style (with `Enumerable` and `#then`) allows to embrace argument deconstruction in its full force:
> ```ruby
> config.then { |host:, port: 8080, **rest|
> ```
> ...which is NOT the main (and obviously not the only) reason to use this style, just a nice side-effect of its consistency with the rest of the language.

+1 Great analysis.


----------------------------------------
Feature #15526: New way to destruct an object hash
https://bugs.ruby-lang.org/issues/15526#change-76267

* Author: alissonbruno.sa (Alisson  Santos)
* Status: Open
* Priority: Normal
* Assignee: 
* Target version: 
----------------------------------------
JavaScript has a nice a neat way to destruct objects.

~~~ javascript
const person = { name: "John Doe", age: 33 };
const { name, age } =  person;
~~~

Erlang has a similar way to destruct a tuple:
~~~ erlang
Person = {"John Doe", 33}
{Name, Age} = Person
~~~

I think it's very handy and would be nice if we have something similar in Ruby.

~~~ ruby
config = { host: 'localhost', port: 3000 } 
{ host, port } = config
~~~

I know Ruby has Hash#values_at, but I think this way it's more readable and understandable

What do you guys think?




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