From: karlvonl <doodpants@...>
Date: 2009-02-21T01:39:41+09:00
Subject: Re: difference between {} and do/end

On Feb 20, 11:25 am, Jeff Schwab <j...@schwabcenter.com> wrote:
> I'm coming back to Ruby after a couple years away, and finding I've
> forgotten some of the basics.  What's the difference between { ... }
> blocks and do ... end blocks?  In particular, why does one of the
> following work, while the other fails?
>
> '%61lice'.gsub! /%(\d+)/ do $1.to_i(16).chr end # => "alice"
> '%61lice'.gsub! /%(\d+)/ {  $1.to_i(16).chr   } # => SyntaxError

It has to do with operator precedence. {...} has high precedence,
while do ... end has low precedence. So in your examples above, the
do...end block is pased to the gsub! method, while the {...} block is
passed to the regex. You can fix the second example using parens:

'%61lice'.gsub!(/%(\d+)/) {  $1.to_i(16).chr   } => "alice"