Clarification of how controllers and views work together...
hutch at recursive.ca
Sat Mar 17 15:16:05 EDT 2007
On 17-Mar-07, at 2:10 PM, Ezra Zygmuntowicz wrote:
> On Mar 17, 2007, at 7:42 AM, Bob Hutchison wrote:
>> Hi Ezra,
>> On 12-Mar-07, at 3:01 AM, Ezra Zygmuntowicz wrote:
>>> Ok I took a look. Here is a patch for you to try before I commit
>>> it to the repo. The default behavior remains the same and the
>>> viewcontext is cached for subsequest renders. But if you pass
>>> in :clean_context => true along with your render method you
>>> will get a fresh context with your current ivars as you expect.
>> That worked perfectly. Thanks!
>> Just wondering... what do you gain by caching the ViewContext?
>> Well, more precisely, when would the output of the render be
>> different when using the cached ViewContext? Doesn't the
>> ViewContext pretty much control the input to the rendering? ... I
>> suppose some of the view's input could be computed by calls (that
>> changed the state of something, otherwise the result of the call
>> would always be the same) made by the view but is that a good idea?
> Hey Bob-
> If we don't cache the view context then layouts will not work
> properly. The views that have layouts are rendered in a 2 step
> process. First the inner template is rendered and an instance var
> is set on the cached view context so when the layout gets rendered
> that ivar is expanded to the layout content. If the view context is
> not cached the layout will be empty, and its a performance hit to
> copy ivars over twice.
Coincidentally I'm not using layouts, so I didn't seen any problems :-)
And you can't accomplish the same by caching the result in the case
of layouts? Not via the view context, but an option maybe?
> You will notice rails does something similar by only allowing you
> to render once. I don't limit you to rendering once and merb
> renders just return strings and merb actions send whatever their
> return value is to the browser.
I certainly did notice and I think what you've done is a very good
idea. Very handy. I'm doing stuff in Merb that I can't do in Rails so
I'm happy. I think this is a pretty nice feature that you should draw
a bit of attention to.
> -- Ezra Zygmuntowicz-- Lead Rails Evangelist
> -- ez at engineyard.com
> -- Engine Yard, Serious Rails Hosting
> -- (866) 518-YARD (9273)
Bob Hutchison -- tumblelog at <http://
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