Comments on: 3 times ActiveSupport 3

By: iain.nl » Monkey Patch of the Month: group_by

iain.nl » Monkey Patch of the Month: group_by — Fri, 19 Mar 2010 15:10:33 +0000

[...] while back, I talked about new additions to ActiveSupport. And now, I have a confession to make: I like monkey patches! At least, as long as they’re [...]

By: Iain Hecker

Iain Hecker — Sun, 14 Feb 2010 23:00:46 +0000

You never have to rely on both obj.nil? and obj.blank? as blank? will check for nil? too…

Anyway, there are a lot of plugins and gems still not working on Rails 3. I wouldn’t upgrade your app just yet. If you have plugins, please make sure they work and put a notice on http://railsplugins.org/

I backport some of the useful ActiveSupport features from Rails 3 into existing Rails 2 apps.

By: CodeJoust - Iain

CodeJoust - Iain — Sun, 14 Feb 2010 18:20:50 +0000

Looks good – I know that rails 3.0beta1 is trunk, but any idea on when it will be released as a final release? Is it a good idea to start writing apps in it, or should I wait for the final release?
I really like the changes, and it’ll be nicer to use more ruby to condense the code instead of relying on something else, along with shortcuts like present?, and various helper methods to replace ‘unless obj.nil? || obj.blank?’.

By: zigzag

zigzag — Thu, 04 Feb 2010 09:07:21 +0000

@Iain Hecker
Yes, you are right.

I read it again, from the your “post name” example i figured out what the usage it is.
Thanks.

By: Iain Hecker

Iain Hecker — Thu, 04 Feb 2010 08:25:36 +0000

@zigzag you're wrong, because uniq_by isn't just about it's boolean value, but also other values, like string. For example:

posts.uniq_by { |post| post.name.downcase }

This is why the results of the block are used as keys in the temporary hash. I think the description in my post wasn't really accurate. It's not a select in that it's not important if the block returns true or false. It will even treat false and nil differently:

[ true, false, nil, 1, 2, nil, 2, false ].uniq_by { |x| x }
#=> [ true, false, nil, 1, 2 ]

By: Caffeine Driven Development » Blog Archive » L33t Links #76

Caffeine Driven Development » Blog Archive » L33t Links #76 — Thu, 04 Feb 2010 07:18:56 +0000

[...] 3 times ActiveSupport 3, “3 random new methods added to ActiveSupport” [...]

By: zigzag

zigzag — Thu, 04 Feb 2010 04:01:45 +0000

or Maybe this version is more readable:

def uniq_by hash, array = {}, [] each { |i| hash[i] ||= (array << i) if yield(i)} array end

By: zigzag

zigzag — Thu, 04 Feb 2010 03:58:02 +0000

[ 1, 2, 3, 4 ].uniq_by(&:odd?) # => [ 1, 2 ]

Is it right?

I checked the source code, it is written
def uniq_by hash, array = {}, [] each { |i| hash[yield(i)] ||= (array << i) } array end
I think it should be:
def uniq_by hash, array = {}, [] each { |i| !yield(i) || hash[i] ||= (array << i) } array end