From: Daniel Carrera <dcarrera@...>
Date: 2003-01-28T10:04:25+09:00
Subject: Re: Parsing: x = y || raise "error"

dir = ARGV.shift || raise "Require directory argument"

Is probably getting parsed as:

dir = (ARGV.shift || raise) "Require directory argument"

When you type

dir = ARGV.shift || raise("Require directory argument")

Ruby parses it as

dir = ARGV.shift || (raise("Require directory argument"))

Use 'or' instead of ||, it has lower precedence.


On Tue, Jan 28, 2003 at 09:55:59AM +0900, Gavin Sinclair wrote:
> I more or less commonly use the following idiom (taken from recent
> code):
> 
>   dir = ARGV.shift || raise "Require directory argument"
> 
> Then I find that it fails:
> 
>   /home/gavin/bin/ckcr:3: parse error
>   /home/gavin/bin/ckcr:3: warning: useless use of a literal in void context
> 
> This fixes it:
> 
>   dir = ARGV.shift || raise("Require directory argument")
> 
> Can anyone explain why the parentheses are required?  Not a critical
> error or anything.  I've just always wanted to know but been afraid to
> ask.
> 
> Regards,
> Gavin
> 
> 

-- 
Daniel Carrera
Graduate Teaching Assistant.  Math Dept.
University of Maryland.  (301) 405-5137