# New, but this seems odd **URL:** \ **Category:** Ruby\ **Created:** [July 7, 2010, 3:02pm UTC](https://www.ruby-forum.com/t/new-but-this-seems-odd/191205 "2010-07-07T15:02:47Z")\ **Posts on this page:** 6\ **Page:** 1
**Author:** ![rawroe](https://www.ruby-forum.com/letter_avatar_proxy/v4/letter/r/94ad74/32.png) [@rawroe](https://www.ruby-forum.com/u/rawroe)\ **Post date:** [July 7, 2010, 3:02pm UTC](https://www.ruby-forum.com/t/new-but-this-seems-odd/191205/1 "2010-07-07T15:02:47Z")
Ok, granted that I’m pretty new to ruby, but this seems odd to me: irb(main):001:0\> x = [1,2,3] =\> [1, 2, 3] irb(main):002:0\> x.delete 2 =\> 2 irb(main):003:0\> x =\> [1, 3] With this behavior, wouldn’t “delete!” be a more appropriate name? ---
**Author:** ![rawroe](https://www.ruby-forum.com/letter_avatar_proxy/v4/letter/r/94ad74/32.png) [@rawroe](https://www.ruby-forum.com/u/rawroe)\ **Post date:** [July 7, 2010, 3:26pm UTC](https://www.ruby-forum.com/t/new-but-this-seems-odd/191205/2 "2010-07-07T15:26:13Z")
On Jul 7, 2010, at 9:01 AM, Andrew W. wrote: > Ok, granted that I’m pretty new to ruby, but this seems odd to me: > > irb(main):001:0\> x = [1,2,3] > =\> [1, 2, 3] > irb(main):002:0\> x.delete 2 > =\> 2 > irb(main):003:0\> x > =\> [1, 3] > > With this behavior, wouldn’t “delete!” be a more appropriate name? Read [http://dablog.rubypal.com/2007/8/15/bang-methods-or-danger-will-rubyist](http://dablog.rubypal.com/2007/8/15/bang-methods-or-danger-will-rubyist) Is there some kind of interpretation of “delete” that doesn’t imply the receiving object will be changed? Compare Hash#update and Hash#merge, for example. Hash#update changes the receiving hash, which Hash#merge creates a new hash with extra/ overwritten keys from the argument hash. It shouldn’t be too surprising that Hash#merge! is an alias of Hash#update. -Rob Rob B. removed\_email\_address@domain.invalid [http://AgileConsultingLLC.com/](http://AgileConsultingLLC.com/) removed\_email\_address@domain.invalid [http://GaslightSoftware.com/](http://GaslightSoftware.com/) ---
**Author:** ![rawroe](https://www.ruby-forum.com/letter_avatar_proxy/v4/letter/r/94ad74/32.png) [@rawroe](https://www.ruby-forum.com/u/rawroe)\ **Post date:** [July 7, 2010, 3:25pm UTC](https://www.ruby-forum.com/t/new-but-this-seems-odd/191205/3 "2010-07-07T15:25:03Z")
On Wed, Jul 07, 2010 at 10:01:35PM +0900, Andrew W. wrote: > Ok, granted that I’m pretty new to ruby, but this seems odd to me: > > irb(main):001:0\> x = [1,2,3] > =\> [1, 2, 3] > irb(main):002:0\> x.delete 2 > =\> 2 > irb(main):003:0\> x > =\> [1, 3] > > With this behavior, wouldn’t “delete!” be a more appropriate name? This came up a few days ago: removed\_email\_address@domain.invalid David A. Black’s answer covers it nicely, I think. Dan ---
**Author:** ![rawroe](https://www.ruby-forum.com/letter_avatar_proxy/v4/letter/r/94ad74/32.png) [@rawroe](https://www.ruby-forum.com/u/rawroe)\ **Post date:** [July 7, 2010, 3:44pm UTC](https://www.ruby-forum.com/t/new-but-this-seems-odd/191205/4 "2010-07-07T15:44:22Z")
On Wed, Jul 7, 2010 at 8:25 AM, Rob B. [removed\_email\_address@domain.invalid](mailto:removed_email_address@domain.invalid)wrote: > > =\> [1, 3] > > receiving object will be changed? x = “123” x.delete ‘2’ # =\> “13” x # =\> “123” ---
**Author:** ![rawroe](https://www.ruby-forum.com/letter_avatar_proxy/v4/letter/r/94ad74/32.png) [@rawroe](https://www.ruby-forum.com/u/rawroe)\ **Post date:** [July 7, 2010, 3:40pm UTC](https://www.ruby-forum.com/t/new-but-this-seems-odd/191205/5 "2010-07-07T15:40:51Z")
That article is helpful, thanks. Somehow I had exactly that idea in my mind, that the ! implies side effects. I was expecting to get back a new array [1, 3], and that there would be a delete! method defined with the below behavior. That seems more consistent to me than some vague description that ! means “dangerous” for some value of “dangerous”. I guess I still have plenty to learn. Thanks for the link! On Wed, Jul 7, 2010 at 9:25 AM, Rob B. ---
**Author:** ![rawroe](https://www.ruby-forum.com/letter_avatar_proxy/v4/letter/r/94ad74/32.png) [@rawroe](https://www.ruby-forum.com/u/rawroe)\ **Post date:** [July 9, 2010, 4:50pm UTC](https://www.ruby-forum.com/t/new-but-this-seems-odd/191205/6 "2010-07-09T16:50:49Z")
On Jul 7, 8:01 am, Andrew W. [removed\_email\_address@domain.invalid](mailto:removed_email_address@domain.invalid) wrote: > With this behavior, wouldn’t “delete!” be a more appropriate name? On Jul 7, 8:25 am, Rob B. [removed\_email\_address@domain.invalid](mailto:removed_email_address@domain.invalid) wrote: > Is there some kind of interpretation of “delete” that doesn’t imply > the receiving object will be changed? After some reflection, I can certainly see how you would expect a bang! there… when working with sets, you often want to manipulate a set to form a different one. guests = [‘removed\_email\_address@domain.invalid’, ‘removed\_email\_address@domain.invalid’, ‘removed\_email\_address@domain.invalid’, ‘me’] invitations\_to\_send = guests.delete(‘me’) and in fact there are enumerable operators that work that way… guest\_emails = [‘removed\_email\_address@domain.invalid’, ‘removed\_email\_address@domain.invalid’, ‘removed\_email\_address@domain.invalid’, ‘me’] guests = guest\_emails.map{|email| Person.find\_by\_email( email ) } whereas guest\_emails.map!{|email| Person.find\_by\_email( email ) } So, yes, inconsistent. Sorry, not much that can be done now… 🙂 The way to do this would be … invitations\_to\_send = guests - [‘me’] or just overwrite delete for your app… 🙂 jw * * * Johnathon W. Web Application Consultant [http://www.mustmodify.com/](http://www.mustmodify.com/)