# Hash questions **URL:** \ **Category:** ruby-talk\ **Created:** [9 April 2009 14:18 UTC](https://rubytalk.org/t/hash-questions/52763 "2009-04-09T14:18:09Z")\ **Posts on this page:** 7\ **Page:** 1
**Author:** ![Hunt\_Jon](https://avatars.discourse-cdn.com/v4/letter/h/ea5d25/32.png) [@Hunt\_Jon](https://rubytalk.org/u/Hunt_Jon)\ **Post date:** [9 April 2009 14:18 UTC](https://rubytalk.org/t/hash-questions/52763/1 "2009-04-09T14:18:09Z")
When I run: p {"foo" =\> 1, "bar" =\> 2, "baz" =\> 3 } I get an error. But when I run: x = {"foo" =\> 1, "bar" =\> 2, "baz" =\> 3 } p x There's no error. What's the difference between the two? John ---
**Author:** ![Todd\_Benson](https://avatars.discourse-cdn.com/v4/letter/t/34f0e0/32.png) [@Todd\_Benson](https://rubytalk.org/u/Todd_Benson)\ **Post date:** [9 April 2009 14:28 UTC](https://rubytalk.org/t/hash-questions/52763/2 "2009-04-09T14:28:48Z")
p( {"foo" =\> 1, "bar" =\> 2, "baz" =\> 3} ) You need parentheses in the first case, I believe, so the that the parser knows you are not trying to send a block to the method #p. Todd > **···** > > On Thu, Apr 9, 2009 at 9:18 AM, Hunt Jon \ wrote: > > > When I run: > > > > p {"foo" =\> 1, "bar" =\> 2, "baz" =\> 3 } > > > > I get an error. > > > > But when I run: > > > > x = {"foo" =\> 1, "bar" =\> 2, "baz" =\> 3 } > > p x > > > > There's no error. > > > > What's the difference between the two? > > > > John ---
**Author:** ![Adam\_Gardner](https://avatars.discourse-cdn.com/v4/letter/a/f08c70/32.png) [@Adam\_Gardner](https://rubytalk.org/u/Adam_Gardner)\ **Post date:** [9 April 2009 14:33 UTC](https://rubytalk.org/t/hash-questions/52763/3 "2009-04-09T14:33:18Z")
Hunt Jon wrote: > When I run: > > p {"foo" =\> 1, "bar" =\> 2, "baz" =\> 3 } > > I get an error. > > But when I run: > > x = {"foo" =\> 1, "bar" =\> 2, "baz" =\> 3 } > p x > > There's no error. > > What's the difference between the two? > > John From what I can tell, ruby is interpreting the beginning of your hash as the beginning of a block, instead; p({"foo" =\> 1, "bar" =\> 2, "baz" =\> 3 }) works as intended. This is seems like a bug to me, although whether it's a bug with the parser (finding a block where it should be looking for a hash literal), a bug with p (asking for a block when it doesn't use one) or the documentation (failing to mention that p accepts a block), I'm not sure. > **···** > > -- > Posted via [http://www.ruby-forum.com/\](http://www.ruby-forum.com/%5C). ---
**Author:** ![Adam\_Gardner](https://avatars.discourse-cdn.com/v4/letter/a/f08c70/32.png) [@Adam\_Gardner](https://rubytalk.org/u/Adam_Gardner)\ **Post date:** [9 April 2009 14:35 UTC](https://rubytalk.org/t/hash-questions/52763/4 "2009-04-09T14:35:31Z")
> From what I can tell, ruby is interpreting the beginning of your hash as > the beginning of a block, instead; > p({"foo" =\> 1, "bar" =\> 2, "baz" =\> 3 }) works as intended. > > This is seems like a bug to me, although whether it's a bug with the > parser (finding a block where it should be looking for a hash literal), > a bug with p (asking for a block when it doesn't use one) or the > documentation (failing to mention that p accepts a block), I'm not sure. Actually, on a bit more inspection, both puts and print work the same way, and I imagine there are other methods that do this as well. This just seems like the parser failing to correctly interpret the ambiguity of a {. > **···** > > -- > Posted via [http://www.ruby-forum.com/\](http://www.ruby-forum.com/%5C). ---
**Author:** ![Rick\_DeNatale1](https://avatars.discourse-cdn.com/v4/letter/r/bbce88/32.png) [@Rick\_DeNatale1](https://rubytalk.org/u/Rick_DeNatale1)\ **Post date:** [9 April 2009 14:44 UTC](https://rubytalk.org/t/hash-questions/52763/5 "2009-04-09T14:44:53Z")
No, I'd say that the parser is correctly parsing an initial '{' after a method invocation as a block argument to the invocation. There's no need to mention that p, or any other method can be given a block since ANY ruby method can be given (and by default) ignore a block. It's just part of the language that you need to learn, like the need to use self.x = value to invoke an attribute writer method to disambiguate between x= as a method and x as a local variable. > **···** > > On Thu, Apr 9, 2009 at 10:35 AM, Adam Gardner \wrote: > > > \> From what I can tell, ruby is interpreting the beginning of your hash as > > \> the beginning of a block, instead; > > \> p({"foo" =\> 1, "bar" =\> 2, "baz" =\> 3 }) works as intended. > > \> > > \> This is seems like a bug to me, although whether it's a bug with the > > \> parser (finding a block where it should be looking for a hash literal), > > \> a bug with p (asking for a block when it doesn't use one) or the > > \> documentation (failing to mention that p accepts a block), I'm not sure. > > > > Actually, on a bit more inspection, both puts and print work the same > > way, and I imagine there are other methods that do this as well. This > > just seems like the parser failing to correctly interpret the ambiguity > > of a {. > > -- > Rick DeNatale > > Blog: [http://talklikeaduck.denhaven2.com/](http://talklikeaduck.denhaven2.com/) > Twitter: [http://twitter.com/RickDeNatale](http://twitter.com/RickDeNatale) > WWR: [http://www.workingwithrails.com/person/9021-rick-denatale](http://www.workingwithrails.com/person/9021-rick-denatale) > LinkedIn: [http://www.linkedin.com/in/rickdenatale](http://www.linkedin.com/in/rickdenatale) ---
**Author:** ![Robert\_K1](https://yyz1.discourse-cdn.com/flex029/user_avatar/rubytalk.org/robert_k1/32/1830_2.png) [@Robert\_K1](https://rubytalk.org/u/Robert_K1)\ **Post date:** [9 April 2009 14:50 UTC](https://rubytalk.org/t/hash-questions/52763/6 "2009-04-09T14:50:04Z")
Here's an alternative p( "foo" =\> 1, "bar" =\> 2, "baz" =\> 3 ) And no, the observed behavior is not a bug as Rick pointed out. Cheers   robert > **···** > > On 09.04.2009 16:44, Rick DeNatale wrote: > > > [Note: parts of this message were removed to make it a legal post.] > > > > On Thu, Apr 9, 2009 at 10:35 AM, Adam Gardner \wrote: > > > > > > From what I can tell, ruby is interpreting the beginning of your hash as > > > > the beginning of a block, instead; > > > > p({"foo" =\> 1, "bar" =\> 2, "baz" =\> 3 }) works as intended. ---
**Author:** ![Phlip1](https://avatars.discourse-cdn.com/v4/letter/p/df788c/32.png) [@Phlip1](https://rubytalk.org/u/Phlip1)\ **Post date:** [9 April 2009 14:55 UTC](https://rubytalk.org/t/hash-questions/52763/7 "2009-04-09T14:55:03Z")
Robert Klemme wrote: > p( "foo" =\> 1, "bar" =\> 2, "baz" =\> 3 ) > > And no, the observed behavior is not a bug as Rick pointed out. The freedom to skip () parens nearly everywhere comes at a price. You gotta think of the space following a method name as a tiny little operator meaning "introduce arguments here like a ( would have".