From: Jason Roelofs <jameskilton@...>
Date: 2006-10-19T00:32:12+09:00
Subject: Re: My first feeling of Ruby

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Frankly I never knew you could do "test #@@varname". I've always used the
#{} syntax.

As for part 2, that is purely an issue with the parser.

hash = "A" => 1, "B" => 2

- Where would the parser end? Ruby allows this:

a, b = 1, 2

so your attempt at assigning a hash as such is a syntax error, as you found
out. As function calls however:

def func1(options = {}); ... ; end

you're allowed to do what seems to be the same thing because the parser is
now grabbing parameters until the end of the line:

func1 :key => '1', :key2 => '2'

is the same as

func1(:key => '1', :key2 => '2')

is the same as

func1( {:key => '1', :key2 => '2'} )

As for "Hmm why [ "A"=>1 , "B"=>2 ] silently produce [{"A"=>1, "B"=>2}] ?",
the parser sees that you want an array. Arrays don't have keys and so for
the same reason as the function parameter syntax, it sees key/value pairs
and creates a hash.

Jason

On 10/18/06, Florent Guiliani <fguiliani@perinfo.com> wrote:
>
> Hi all,
>
> Today I'm learning Ruby. Globally It's a great programming langage but
> I've noticed some irrationnal things:
>
> First thing:
> ============
> irb(main):138:0* class Toto
> irb(main):139:1>    @@test="a"
> irb(main):140:1>
> irb(main):141:1*    def test
> irb(main):142:2>      @test="b"
> irb(main):143:2>      test="c"
> irb(main):144:2>      puts "test #@@test"
> irb(main):145:2>      puts "test #@test"
> irb(main):146:2>      puts "test #test"    # #{test} instead #test why?
> irb(main):147:2>    end
> irb(main):148:1> end
> => nil
> irb(main):149:0> Toto.new.test
> test a
> test b
> test #test
> => nil
>
> Why #test doesn't work for local variables? It would be more logic. It's
> my point of view. We can have both #test and #{test} working.
>
>
> Second thing:
> =============
> hastables is using a mix of {} and []. Always using {} or [] (but not
> both) for hastable would be "errorless".
>
> Actually {} for initialisation:
> irb(main):150:0> hash = { "A"=>1 , "B"=>2 }
> => {"A"=>1, "B"=>2}
>
> [] for reading:
> irb(main):152:0> hash["A"]
> => 1
>
> If you go wrong:
> irb(main):156:0> hash{"A"}
> => 537984250
> irb(main):154:0> hash = [ "A"=>1 , "B"=>2 ]
> => [{"A"=>1, "B"=>2}]
>
> I would prefer an error or warning. The last line means I can omit {}?
> so let's go on:
>
> irb(main):155:0> hash = "A"=>1 , "B"=>2
> SyntaxError: compile error
> (irb):155: parse error, unexpected tASSOC, expecting $
> hash = "A"=>1 , "B"=>2
>              ^
>          from (irb):155
>          from :0
> irb(main):156:0>
>
> Hmm why [ "A"=>1 , "B"=>2 ] silently produce [{"A"=>1, "B"=>2}] ?
>
> my 2c,
> Florent,
>
>

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