From: John Gabriele <jmg3000@...>
Date: 2006-10-13T06:33:20+09:00
Subject: Ruby expressions vs. values (like Perl?)

Does Ruby use the same terminology as Perl with regard to expressions
versus values?

I read a great MJD comment on PerlMonks a while back (
http://www.perlmonks.org/?node_id=72263 ). That comment notes how, in
Perl, one needs to be well aware of the difference between expressions
(the things you type into your code), and values (the things the
interpreter evaluates expressions to).

It seems that, the big reason for watching the difference between
expressions and values in Perl is because expressions turn into
different values at runtime depending upon context.

So, back to Ruby, I believe that the rhs of the following statement is
an "Array expression":

irb(main):001:0> foo = ['a','bee','sea']
=> ["a", "bee", "sea"]

but, what kind of expression is the rhs of the following:

irb(main):002:0> bar = 'dee', 'ee', 'eff'
=> ["dee", "ee", "eff"]

?

Incidentally, I also note that this one -- although performing
parallel assignment -- also happens to be generating an Array value:

irb(main):003:0> zz = ( a, b, c = 'gee', 'aitch', 'aye' )
=> ["gee", "aitch", "aye"]

irb(main):004:0> zz
=> ["gee", "aitch", "aye"]

According to irb, the Array gets generated even if you leave off the
"zz =" and the parentheses. Seems like extra work for the interpreter
to go through (making that Array), just to do a parallel assignment,
no?

Thanks,
---John