What does ! mean in front of a method?

Question

What does it mean when the bang method is in front? What is this shorthand for?

!post.save

Is it the same as [this](http://stackoverflow.com/questions/612189/why-are-exclamation-marks-used-in-ruby-methods)? I don't know Ruby. — Ry-, Jan 24 '12 at 19:13
@KL-7: You're right, it's not. I can't believe I didn't notice that. — Ry-, Jan 24 '12 at 19:15

score 6 · Answer 1 · answered Jan 24 '12 at 19:14

6

It's a negation. In your example it means to NOT the result of post.save.

if:

post.save => true
!post.save => false

otherwise:

post.save => false
!post.save => true

answered Jan 24 '12 at 19:14

TreyE

2,489
21
23

score 6 · Accepted Answer · answered Jan 24 '12 at 19:20

It is equivalent to

not post.save

Usually used in if clauses, like:

if !post.save               #if the post could not be saved for some reason
   puts 'could not save post!'
end

It's because the function save from ActiveResource::Base returns true if the POST request succeeded and false if it didn't. Read here for some more information about the function.

What does ! mean in front of a method?

2 Answers2