erlyweb uses a component system for rendering pages. It makes most of
my controller functions return lists like this:
[{data,post:title(Post)},
{ewc,post,contents,[A,Post]},
{ewc,comment,comments,[A,post:comments(Post)]}]
The view function then looks like:
<%@ show([Title,Contents,Comments]) %>
<h1><% Title %></h1>
<div class="post_contents"><% Contents %></div>
<ul class="comments><% Comments %></ul>
I really like this, because it allows me to separate the view-logic
for things like contents and comments out from each other, which
makes changing the behaviour of these quite simple, localised, and re-
useable. (In fact, as I re-write portions of erlyweb for my purposes,
the component system is something that I haven't touched at all
because it works quite well.) However, it has an inherent limitation:
none of those functions can return data to be rendered outside of
their components. In my case, I'd like to be able to set <title>
tags, which means that the top-level controller function (by top-
level, I mean the one referenced in the URL; like in /post/show/12,
the top-level controller function would be show/2) needs to somehow
return information to be rendered outside its little sandbox.
I see that Vimagi doesn't set <title> tags (neither <http://
vimagi.com/p/0PXmMRe6hGV> nor <http://vimagi.com/users/feeling3_4>
set one, at least, and those are where I'd expect to see them), but
BeerRiot does (<http://beerriot.com/beer/view/1751>; BTW I do love
the idea of having a controller called "beer_controller").
It isn't limited to <title>s (for instance, I may want to alert the
browser that an RSS equivalent of this page exists, or what the
caching TTL is for this page in the HTTP headers). Conceptually, how
would one go about returning this extra information, while still
using the component system (I now have a lot of code that uses it
that I'd like to not re-write :) )?
