From: Justin Collins <justincollins@...>
Date: 2008-01-18T10:41:23+09:00
Subject: Re: Ruby syntax in "respond_to do |format| line -- can clari

Joshua Beall wrote:
> Justin Collins wrote:
>   
>> Joshua Beall wrote:
>>     
>>>> ...and you imagine executing it as a method, the block variable,
>>>>         
>>>       format.html # index.html.erb
>>> And it should work.  And indeed it does.  However, there are still 
>>> posts_controller.rb:9: syntax error, unexpected tSYMBEG, expecting kDO 
>>> or '{' or '('
>>>
>>> It's complaining about the symbol :xml.
>>>   
>>>       
>> In this case { render :xml => @posts} is being interpreted as a Hash, 
>> not a block and that is messing things up for you.
>>     
>
> So how do I construct the method call so that I can use parentheses?
>   

There is really no reason to do so in most cases, but you can if you 
really want:

    responder = Responder.new(self)
    responder.html
    l = lambda { render :xml => @posts}
    responder.xml(&l)
    responder.respond

The "&" (in this case) says "make this the block that gets passed to the 
method."

I believe you could also do:

    responder.xml(&lambda { render :xml => @posts } )
or
    responder.xml(&Proc.new { render :xml => @posts } )

But, again, this is not the normal way to do it. You can sort of tell, 
because it is much more awkward than

    responder.xml { render :xml => @posts }


Hope that helps some.

-Justin