From: Joel VanderWerf <vjoel@...>
Date: 2006-07-02T09:05:13+09:00
Subject: Re: Is a block converted to a Proc object before yield?

Alexandru Popescu wrote:
> Thanks Joel... it looks like my initial understanding was wrong. It is
> not block.call the one that triggers block to Proc conversion, but in
> fact passing blocks as parameters. Is this the correct understanding?

Right, it happens when the block is passed to a method that expects a 
"&block" argument (or if the method explicitly calls Proc.new). If you 
are executing "block.call", then "block" is a variable and it, like any 
variable, refers to an object.

It's up to the callee, not the caller, to determine how to treat the 
block: either yield to it or turn it into an object. The former has a 
small performance advantage (and yield is an elegant notation). The 
latter allows the Proc object to be saved away somewhere and called even 
after the method has finished.

-- 
       vjoel : Joel VanderWerf : path berkeley edu : 510 665 3407