From: Devin Mullins <twifkak@...>
Date: 2005-09-27T06:53:35+09:00
Subject: Re: Embedded Ruby and Tag Libs

Hi, Adam,

First, DHH's opinion on this matter might be of interest to you:
http://www.loudthinking.com/arc/000408.html
(DHH = The Rails Guy, btw)

Second, the best way I can think of to achieve something like what 
you're talking about in ERB would look like this:

class AvTable
  def initialize(out)
    @out = out; @side = :odd
  end
  def trow
    @out << %Q{<tr class="#@side">}
    yield
    @out << "</tr>\n"
    @side = (@side == :odd) ? :even : :odd
  end
end

def av_table(out)
  out << "<table>\n"
  yield AvTable.new(out)
  out << "</table>\n"
end

a = ERB.new <<RHTML
<% av_table(_erbout) do |av| %>
  <% av.trow do %><td>...</td><% end %>
  <% av.trow do %><td>...</td><% end %>
  <% av.trow do %><td>...</td><% end %>
  <% av.trow do %><td>...</td><% end %>
  <% av.trow do %><td>...</td><% end %>
<% end %>
RHTML

a.result.display

Not sure how you would take care of "last", though (without writing an 
internal iterator for your data), but I'm no expert, and this is 
probably a crappy way of achieving what you're after. (I, for instance, 
am not a fan of passing around _erbout.)

Devin

Adam Van Den Hoven wrote:

> Hey guys,
>
> I've been dabbling with ruby on and off for a year or so and recently  
> more often. At work we do Java development and I keep thinking that  
> it would be nice to be able to bring some of the stuff I designed  
> there into my own work, which I want to do in ruby.
>
> I was wondering if anyone had thought about adding something like the  
> Java TagLibs to ruby (I guess it would embedded ruby). In my case, it  
> would make long term maintenance of files MUCH easier as I can give  
> it to a non-technical person without much documentation. In most  
> cases people who don't understand programming do understand parts of  
> HTML markup. If I could hide what is currently inline code behind  
> things that look like tags, its easier to give maintenance over to  
> non-technical folks.
>
> Here's a simple example. Often you want to do tiger striping on  
> tables (alternate background color on each row). Because there isn't  
> sufficiently wide spread support for CSS2 and CSS3 selectors, you  
> tend to do the following:
>
> <table>
>         <tr class="odd"><td>...</td></tr>
>         <tr class="even"><td>...</td></tr>
>         <tr class="odd"><td>...</td></tr>
>         <tr class="even"><td>...</td></tr>
>         <tr class="odd"><td>...</td></tr>
>         <tr class="even last"><td>...</td></tr>
> </table>
>
> Unfortunately, if you want to add something between rows 4 and 5 you  
> need to reset all your classes. This can get complicated. However, if  
> I had a taglib I could ask my content authors to write the following:
>
> <av:table>
>     <av:trow><td>...</td></av:trow >
>     <av:trow><td>...</td></av:trow >
>     <av:trow><td>...</td></av:trow >
>     <av:trow><td>...</td></av:trow >
>     <av:trow><td>...</td></av:trow >
>     <av:trow><td>...</td></av:trow >
> </av:table>
>
> And leave the generation up to the code.
>
> I can think of hundreds of specific tags I might create, depending on  
> the situation, which would make authoring content easier and would  
> give me better control over the rendering of a page. It could also  
> make writing code easier in general. It would also be useful to have  
> many of the tags defined in the JSTL.
>
> Just a thought I had.
> Adam
>
>