Ruby Method of the Month 2010.05. Lightning talk for the Columbus Ruby Brigade.

1. empty?, nil?, blank? & present?
Method of the Month
Kevin Munc
@muncman

2. empty?
There’s a lot of empty?!
20 matches in my local copy of
RailsAPI.
Including versions on: Array, Hash,
Set, String, and more.

3. empty?
The Gist: returns true if the type is
empty. (Surprise!)

4. empty?
The Gist: returns true if the type is
empty. (Surprise!)
“”.empty? == true
{}.empty? == true
[].empty? == true

5. empty?
The Gist: returns true if the type is
empty. (Surprise!)
“ ”.empty?
“”.empty? == true == false
{}.empty? == true [nil,nil].empty?
== false
[].empty? == true {:k=>nil}.empty?
== false

6. nil?
nil? is kinda minimal.
Only two occurrences in my copy of
the RailsAPI.
On NilClass and Object.
(Both from the object.c source file.)
(http://ruby-doc.org/doxygen/1.8.4/object_8c-source.html)

7. nil?
“Only the object nil responds true to
nil?” - RailsAPI

8. nil?
“Only the object nil responds true to
nil?” - RailsAPI
nil.nil? == true
anything_else.nil? == false

9. blank?
blank? is filled in by Rails.
Added by ActiveSupport.
On Object.

10. blank?
blank? is true if the target is false,
empty?, nil?, or all whitespace.

11. blank?
blank? is true if the target is false,
empty?, nil?, or all whitespace.
“”.blank? == true
{}.blank? == true
[].blank? == true

12. blank?
blank? is true if the target is false,
empty?, nil?, or all whitespace.
“ “.blank? == true
“”.blank? == true
“t”.blank? == true
{}.blank? == true
nil.blank? == true
[].blank? == true
false.blank? == true

13. present?
present? is another gift from
ActiveSupport.
It appears in one class in RailsAPI.
On Object.

14. present?
The opposite of blank? (That’s not a
question.)

15. present?
The opposite of blank? (That’s not a
question.)
# File activesupport/lib/active_support/core_ext/object/blank.rb, line 17
# (Ruby 1.9)
17: def present?
18: !blank?
19: end

16. http://www.flickr.com/photos/st3f4n/3556697439/in/set-72157616350171741//
Questions?