From: Gregory Brown <gregory.t.brown@...>
Date: 2008-08-02T05:40:30+09:00
Subject: Re: Help finding this syntax error

On Fri, Aug 1, 2008 at 4:33 PM, Adam Shelly <adam.shelly@gmail.com> wrote:
> On 8/1/08, Patrick Li <patrickli_2001@hotmail.com> wrote:
>> Nope. that's not quite it. i'm really quite stumped.
>>
>> syntax error, unexpected tSYMBEG, expecting ')' (SyntaxError)
>>    if(FieldTypes.key? field && FieldTypes[field].respond_to? :select)
>>                                                               ^  from
>> -e:1
>
> Apparently the parser just can't recognize function calls inside
> conditions unless they have the parens:
>
> irb(main):013:0> if (true && p 1)
> irb(main):014:1> p :hi; end
> SyntaxError: compile error
> (irb):13: syntax error, unexpected tINTEGER, expecting kDO or '{' or '('
> if (true && p 1)

This isn't actually the case, it has to do with the fact that && binds tightly.
'and' and 'or' have less tight binding and work as you'd expect.

>> if true and p 1
>>   p :hi
>> end
1
:hi

So... if Ruby sees if (true && p 1), it parses it as:
  if ((true && p) 1)

but using if (true and p 1), Ruby sees:

 if (true and p(1))

HTH,

-greg

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