From: Gennady Bystritsky <gfb@...>
Date: 2004-05-02T09:43:20+09:00
Subject: Re: Ruby Newbie (ooh, that rhymes!) - When do I use do/end, when {}?


On May 1, 2004, at 2:33 PM, Mark Hubbart wrote:

>
> On May 1, 2004, at 1:54 PM, Glenn wrote:
>
>> I've read the User Guide and other docs on the net, but I'm a little
>> unsure as to whether I can ALWAYS substitute the DO/END with curly
>> brackets for a block?  For example, I've only ever seen referenced to
>> hash definitions using curlies.  What's the rule here?  Is it purely
>> down to preference?

As somebody has mentioned already it is not only preference, but also 
precedence rules ({} sticks better than do...end, meaning higher 
precedence).

>
> While there is some amount of preference involved, there is a general 
> rule that most Ruby programmers (and matz, I believe) agree on: 
> brackets for one-line blocks, do...end for longer blocks. ie:
>
>   5.times {|n| puts n }

There's also another usage some people, including myself, agree on: 
do...end for blocks that actually DO stuff, like in Array#each, 
File.open, Integer#times (Mark, sorry for contradiction ;-)), etc.; {} 
for blocks that define conditions, like in map, select/reject, sort, 
etc.


Sincerely,
Gennady Bystritsky