From: "chendo (Jack Chen)" <ruby-lang@...>
Date: 2013-09-12T09:54:44+09:00
Subject: [ruby-core:57151] [ruby-trunk - Feature #8895] Destructuring	Assignment for Hash


Issue #8895 has been updated by chendo (Jack Chen).


sawa (Tsuyoshi Sawada) wrote:
> =begin
> Given that destructive assignments with array prohibits the `[ ]` on the left side of the assignment, that is:
> 
>     a, b = [1, 2]
> 
> instead of:
> 
>     [a, b] = [1, 2]
> 
> it would be more consistent if your proposal were:
> 
>     name: name, age: age = {name: "John Smith", age: 42}
> 
> rather than:
> 
>     {name: name, age: age} = {name: "John Smith", age: 42}
> =end

I left the braces in because I felt it would be easier to parse, however if without braces is doable as well, that would work also. Will update the proposal.
----------------------------------------
Feature #8895: Destructuring Assignment for Hash
https://bugs.ruby-lang.org/issues/8895#change-41763

Author: chendo (Jack Chen)
Status: Open
Priority: Normal
Assignee: 
Category: 
Target version: 


=begin
Given Ruby already supports destructuring assignment with Array (a, b = [1, 2]), I propose destructuring assignments for Hash.

== Basic example

  params = {name: "John Smith", age: 42}
  {name: name, age: age} = params

  # name == "John Smith"
  # age == 42

This would replace a common pattern of assigning hash values to local variables to work with.

== General syntax

  { <key-expr> => <variable_name>, ��� } = <object that responds to #[]>

  # Symbols
  { foo: bar } = { foo: "bar" }
  bar == "bar"

  # Potential shorthand
  { foo } = { foo: "bar" }
  foo == "bar"

== Use cases:

  # MatchData
  { username: username, age: age } = "user:jsmith age:42".match(/user:(?<username>\w+) age:(?<age>\d+)/)
  username == "jsmith"
  age == "42"

== Edge cases

  # Variable being assigned to more than once should use the last one
  { foo: var, bar: var } = {foo: 1, bar: 2}
  var == 2

Thoughts?
=end



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