From: "Bartosz Dziewoński" <matma.rex@...>
Date: 2011-12-09T20:25:00+09:00
Subject: Re: Confusing results from string multiplication

Just a note that this might happen not only with multiplication vs
splat operator.

Division vs regex definition can give similar troubles. (Please note
that the parsing is always deterministic, and the interpreter will try
its best guess, using spacing as hints. In Perl, a code like the one
below could parse differently depending on the number of arguments the
function takes.)

irb(main):001:0> def foo; 5; end
irb(main):002:0> foo/2 #/
=> 2
irb(main):003:0> foo / 2 #/
=> 2
irb(main):004:0> foo /2 #/
ArgumentError: wrong number of arguments (1 for 0)
        from (irb):2:in `foo'
        from (irb):4
        from C:/Ruby192/bin/irb:12:in `<main>'


Or with bitwise AND vs the unary to_proc operator:

irb(main):015:0> foo & 6
=> 4
irb(main):016:0> foo &6
TypeError: wrong argument type Fixnum (expected Proc)
        from (irb):16
        from C:/Ruby192/bin/irb:12:in `<main>'



Just code reasonably: when you want to use something as a binary
operator, space equally on its both sides; when you want unary
operator, only space to the left. (Or just use the damn parentheses.)

-- Matma Rex