New Features in Ruby 2.4

#1

Post by jbackus » Thu, Jul 21, 2016, 12:18 AM UTC

New Features in Ruby 2.4
blog.blockscore.com

Re: New Features in Ruby 2.4

#2

Post by saghm » Thu, Jul 21, 2016, 2:51 AM UTC

Some of these are pretty amazing, like the `digits` method and the new OptionParser functionality (which seems to be a sort of standard library equivalent to doctopt!).

That being said, I can't help but shake my head at the section about "multiple assignment of conditionals:

"You can now assign multiple variables within a conditional...You probably shouldn’t do that though."

Am I alone and thinking that it's a little bit hypocritical to specifically add functionality to your language if you don't want people to use it? Or is this just a joke that's gone over my head?

Re: New Features in Ruby 2.4

#3

Post by ukoki » Thu, Jul 21, 2016, 5:05 AM UTC

digits method just saved code-golfers 20 characters.

`num.to_s.split(//).map(&:to_i)` => `num.digits`

Re: New Features in Ruby 2.4

#4

Post by Rafert » Thu, Jul 21, 2016, 7:09 AM UTC

saghm wrote: post #2

Some of these are pretty amazing, like the `digits` method and the new OptionParser functionality (which seems to be a sort of standard library equivalent to doctopt!). That being said, I can't help but shake my head at the section about "multiple assignment of conditionals: "You can now assign multiple variables within a conditional...You probably shouldn’t do that though." Am I alone and thinking that it's a little…

It has a historical reason: https://bugs.ruby-lang.org/issues/10617

Re: New Features in Ruby 2.4

#5

Post by [deleted] » Thu, Jul 21, 2016, 7:11 AM UTC

saghm wrote: post #2

Some of these are pretty amazing, like the `digits` method and the new OptionParser functionality (which seems to be a sort of standard library equivalent to doctopt!). That being said, I can't help but shake my head at the section about "multiple assignment of conditionals: "You can now assign multiple variables within a conditional...You probably shouldn’t do that though." Am I alone and thinking that it's a little…

[deleted]

Re: New Features in Ruby 2.4

#6

Post by jbackus » Thu, Jul 21, 2016, 7:14 AM UTC

saghm wrote: post #2

Some of these are pretty amazing, like the `digits` method and the new OptionParser functionality (which seems to be a sort of standard library equivalent to doctopt!). That being said, I can't help but shake my head at the section about "multiple assignment of conditionals: "You can now assign multiple variables within a conditional...You probably shouldn’t do that though." Am I alone and thinking that it's a little…

Ah well "You probably shouldn’t do that though" is just my opinion as the author. I didn't play a part in these changes. I just like Ruby enough to dig into their changelog :)

Re: New Features in Ruby 2.4

#7

Post by integrii » Thu, Jul 21, 2016, 7:20 AM UTC

Ruby syntax is just getting goofier and goofier.

Re: New Features in Ruby 2.4

#8

Post by kimshibal » Thu, Jul 21, 2016, 7:25 AM UTC

integrii wrote: post #7

Ruby syntax is just getting goofier and goofier.

is this a sign to move to elixir?

Re: New Features in Ruby 2.4

#9

Post by dkarapetyan » Thu, Jul 21, 2016, 7:28 AM UTC

These are all great but when are we getting optional typing? If the js ecosystem wasn't a clown operation my language of choice would be typescript instead of ruby.

Re: New Features in Ruby 2.4

#10

Post by psyklic » Thu, Jul 21, 2016, 7:51 AM UTC

Rafert wrote: post #4

saghm wrote: post #2

Some of these are pretty amazing, like the `digits` method and the new OptionParser functionality (which seems to be a sort of standard library equivalent to doctopt!). That being said, I can't help but shake my head at the section about "multiple assignment of conditionals: "You can now assign multiple variables within a conditional...You probably shouldn’t do that though." Am I alone and thinking that it's a little…

It has a historical reason: https://bugs.ruby-lang.org/issues/10617

To summarize* and elaborate: Originally in Ruby, multiple assignment inside a conditional caused a parse error. Why? Because multiple assignment originally always returned an array:

  irb(main): a, b = nil
  => [nil]

In Ruby, non-empty arrays always evaluate to truthy. (The array above has one element, nil.) Hence, multiple assignment inside a conditional would have been meaningless. For this reason, Ruby threw a parse error.

As of Ruby 1.9, multiple assignment in a conditional now returns whatever the right-hand side of the assignment operator evaluates to. So, it makes sense to re-allow multiple assignment inside conditionals and remove the parse error.

Here are some examples illustrating the return value of multiple assignment. The first two are truthy while the third is falsey:

  irb(main): a, b = 8, 7
  => [8, 7]

  irb(main): a, b = 8
  => 8
  (a = 8, b = nil)

  irb(main): a, b = nil
  => nil
  (a = nil, b = nil)

- The above based on user 'bug hit' who attributes Yusuke Endoh, from https://bugs.ruby-lang.org/issues/10617