Symbols are puzzling me and not only symbols

rubyonrails-talk
1

Dear all, I've got two burning questions. Both regard the manipulation of the params hash. Imagine: params = {"commit"=>"Add comment", "comment"=>{"message"=>"foo", "name"=>"bar", "answer"=>"2", "email"=>"foo@bar"}}

So the params hash has two keys, one('commit') points to a string the other('comment') to an other hash. Normally I can do something like; params[:id] or whatever, now if I do that, params[:commit] it returns nil! Why?? params['commit'] works as expected.

On to the second question, when I have a large array or hash I used to(In Java/PHP etc) split them up in several lines. For example:     tmp = {:message => 'tmp' ,:name => 'tmp' ,:email => 'tmp'}

Would become:     tmp = { :message => 'tmp'                ,:name => 'tmp'                ,:email => 'tmp'              }

I find this eaasier to read and easier to check for comma related errors. However Ruby fails to recognise this, failing with the error: syntax error, unexpected ',', expecting '}'           ,:name => 'tmp'            ^

Ruby is better kidding me. The interpreter doesn't handle whitespace?? Any comments on what I am doing wrong or why not ignoring whitespace is a good idea, I'd love to hear.

With kind regads

2

Hi --

Yeah, ruby doesn't care about spaces, but it does care about new lines. Which is good, at least it doesn't rely on semi-colons.

There are some cases where spaces matter; for example:

irb(main):002:0> puts (3) + 2 5 => nil irb(main):003:0> puts(3) + 2 3 NoMethodError: undefined method `+' for nil:NilClass

In the second one, it evaluated puts(3) (including actually puts'ing 3) and then tries to add 2 to it, which fails.

Also:

irb(main):004:0> puts puts (3) (irb):4: warning: don't put space before argument parentheses 3 nil

which does the same as puts puts(3) but gives you that warning.

for a multiline declaration with clarity of commas

tmp = {    :message => 'tmp' ,    :name => 'tmp' ,    :email => 'tmp'    }

At the very great risk of sounding curmudgeonly, could I put in a heartfelt plea for people not to do that? It looks bizarre, and seems to invite scrutiny in case there's been some kind of mistake or omission.

David

3

Aha, but why does that scheme break down? Knowing that would prevent me from running future problems. The class documentation()http:// api.rubyonrails.org/classes/HashWithIndifferentAccess.html) does not bring me very far either. Especially the line: [quote] this class has dubious semantics and we only have it so that people can write params[:key] instead of params['key'] [/quote] does not inspire confidence.

4

Hmmm, alright. I still don't understand why the parser does not just run until it encounters an other curly brace (}). But I can live with it.

5

Interesing example! I should use that in class. Thanks.