From: "Peña, Botp" <botp@...>
Date: 2007-02-02T10:28:34+09:00
Subject: Re: Ruby << is ambiguos

From: Wolfgang Nádasi-Donner [mailto:wonado@donnerweb.de] :
# There is a similar problem with "?" and "?:".
# irb(main):001:0> ?2
# => 50

k

# irb(main):002:0> sep = "x" * (true?2:1)
# SyntaxError: compile error
# (irb):2: parse error, unexpected ':', expecting ')'
# sep = "x" * (true?2:1)
#                      ^
#          from (irb):2

careful. "?" is a valid char for identifiers and is also used for inline if.
stupid example,

irb(main):002:0> def true?
irb(main):003:1> true
irb(main):004:1> end
=> nil
irb(main):005:0> true?
=> true
irb(main):006:0> true? 2
ArgumentError: wrong number of arguments (1 for 0)
        from (irb):6:in `true?'
        from (irb):6
irb(main):007:0> true?2
ArgumentError: wrong number of arguments (1 for 0)
        from (irb):7:in `true?'
        from (irb):7
irb(main):008:0> true?2:1
SyntaxError: compile error
(irb):8: parse error, unexpected ':', expecting $
true?2:1
       ^
        from (irb):8
irb(main):009:0> true?2
ArgumentError: wrong number of arguments (1 for 0)
        from (irb):9:in `true?'
        from (irb):9
irb(main):011:0> true? 2:1
SyntaxError: compile error
(irb):11: parse error, unexpected ':', expecting $
true? 2:1
        ^
        from (irb):11
irb(main):012:0> true? ? 2:1
=> 2
irb(main):013:0> true ? 2:1
=> 2

# irb(main):003:0> sep = "x" * (true ?2:1)
# => "xx"

k.

kind regards -botp