From: Josh Cheek <josh.cheek@...>
Date: 2012-02-13T00:13:52+09:00
Subject: Re: the ruby syntax

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On Sun, Feb 12, 2012 at 7:49 AM, maven apache <apachemaven0@gmail.com>wrote=
:

> 2012/2/12 Bartosz Dziewo=C5=84ski <matma.rex@gmail.com>
>
> > When a hash is the last argument to a method, you can skip its open-
> > and close-braces.
> >
> > So this:
> > IO.new("data.txt", mode: 'w:UTF-16LE', cr_newline: true)
> > Is the same as this:
> > IO.new("data.txt", {mode: 'w:UTF-16LE', cr_newline: true})
> >
>
> But in the ruby document:http://www.ruby-doc.org/docs/ProgrammingRuby/
>
> Definiation of a hash should  like this:
>
> {'key'=3D>'value'.....}
>
> Now in the IO.new exmaple,it is written as {key:value}.  Is the ':' symbo=
l
> same as '=3D>'?? I do not find it is methioned in any document.
>
>
So, again, you could figure out the answer to this by writing a method that
simply prints the inspection of its args. Try this:

def meth(arg)
  p arg
end

meth {:a =3D> 'b'}
# ~> -:5: syntax error, unexpected tASSOC, expecting '}'
# ~> ...9178_68393_18610 =3D (meth {:a =3D> 'b'});$stderr.puts("!XMP1329...
# ~> ...                               ^

# hmm, that's strange, what if I do this?
meth({:a =3D> 'b'})
# >> {:a=3D>"b"}

# well that worked, I wonder why (contemplate it for later, or ask if you
can't figure it out)
# now what about those curly braces?
meth(:a =3D> 'b')
# >> {:a=3D>"b"}

# okay, I guess they are the same.
# now I was thinking that the ':' symbol is same as '=3D>', lets see
meth(a: 'b')
# >> {:a=3D>"b"}

# aah, apparently it is... but wait, what if I have a number for a key?
meth(1: 'b')
# ~> -:5: syntax error, unexpected ':', expecting ')'
# ~> meth(1: 'b')
# ~>        ^
# ~> -:5: syntax error, unexpected ')', expecting $end

# Hmm, maybe it only works for symbol arguments
# ... etc ...

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