From: Colin Bartlett <colinb2r@...>
Date: 2010-11-02T20:19:33+09:00
Subject: Re: Strange whitespace parsing behavior on Ruby 1.8.7 (patchlevel 249/302)

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On Tue, Nov 2, 2010 at 7:17 AM, Robert Klemme <shortcutter@googlemail.com>wrote:

>
> Can you repost with proper indentation and line wrapping?
> Guessing from your text I assume you might have fallen
> into a unary / binary operator ambiguity.
>

That seems to be a correct diagnosis. See below for the OP's irb session
with formatting.
For the OP:

7.abs + 3 #=> 10
7.abs+3   #=> 10

7.abs +3   #=> ArgumentError: wrong number of arguments(1 for 0)
## Ruby parses the "+" in " +3" as a unary + on 3 giving integer 3,
## which means that integer 3 is an argument to abs, hence the error
message.

def okp( a, b ); a + b; end  #=> nil

okp(4, 7.abs + 3) #=> 14
okp(4, 7.abs+3)   #=> 14
okp(4, 7.abs +3)  #=> SyntaxError: (irb):23: syntax error,
                          #   unexpected tInteger, expecting ")"
## I leave that - and the next - one to Robert to explain!

x = '123456'  #=> "123456"
x.slice(1, x.size -2)  #=> SyntaxError: compile error(irb):63:
                             # syntax error, unexpected ')',
                             # expecting kDO_BLOCK
                             # from (irb):63 from :0
## Again, the "-" in " -2" is parsed on a unary on 2 giving integer value
-2.
## Why the ')' is unexpected I leave to Robert!


*** the OP's irb session

irb(main):062:0* x = '123456'=> "123456"

irb(main):063:0> x.slice(1, x.size -2)
SyntaxError: compile error(irb):63: syntax error, unexpected ')',
expecting kDO_BLOCK
from (irb):63 from :0

irb(main):064:0> x.slice(1, x.size - 2)=> "2345"

irb(main):065:0> x.slice(1, x.size-2)=> "2345"

irb(main):066:0> x.slice(1, x.size -2)
SyntaxError: compile error(irb):66: syntax error, unexpected ')',
expecting kDO_BLOCK
from (irb):66 from :0

irb(main):067:0> x[x.size -3,1]
ArgumentError: wrong number of arguments (2 for 0)
from (irb):67:in `size' from (irb):67 from :0

irb(main):068:0> x[x.size - 3,1]=> "4"

irb(main):069:0> def ok(a,b)
irb(main):070:1> end=> nil

irb(main):071:0> ok(x.size +3,4)
ArgumentError: wrong number of arguments (2 for 0)
from (irb):71:in `size' from (irb):71 from :0

irb(main):072:0> ok(4,x.size +3)
SyntaxError: compile error(irb):72: syntax error, unexpected ')',
expecting kDO_BLOCK
from (irb):72 from :0

irb(main):074:0> ok(4,x.size + 3)=> nil

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