This is why we use the newline escapes: nested templates don't touch them at
all. Note that your solution still falls down if you have a three-deep
nested template.
If you're using Rails, the best solution would probably be to post-process
the template and change all newline escapes to literal newlines.
As for the extra work in tabs, that's certainly not supposed to be there.
I've gotten rid of it in the repo.
- Nathan
On Feb 8, 2008 8:27 AM, Wincent Colaiuta <[EMAIL PROTECTED]> wrote:
>
> Ok, I've now done a bit more investigation and now understand what
> Haml is doing under the covers.
>
> The reason why my hack manipulating the tabulation didn't work is
> because of the way templates are nested in Rails with Haml.
>
> Basically, let's say you suppress the tabulation in your "show"
> template using the hack shown above. I've found that it's only
> necessary to set @real_tabs to 0, as in the end what's going to get
> called is push_script() and that only cares about @real_tabs, not
> @tabulation.
>
> But what happens next is that your application layout gets rendered,
> and inside it is a yield call that gets the output of the precompiled
> "show" template. This means that the output goes through push_script()
> a second time and you get unwanted indentation again.
>
> This is a tricky issue: you need some way for nested templates to
> communicate upwards to the templates that enclose them, and advise
> them not to meddle with the tabulation.
>
> I've got a new hack that works, but it is terribly ugly. Here it is:
>
> Here's a snippet of my "show" template:
>
> -preserving do
> [EMAIL PROTECTED]
>
> And here's the updated preserving helper:
>
> def preserving &block
> real_tabs = buffer.instance_variable_get :@real_tabs
> buffer.instance_variable_set :@real_tabs, 0
> buffer.buffer << "<!-- Haml: start pre -->\n"
> yield
> buffer.buffer << "<!-- Haml: end pre -->\n"
> buffer.instance_variable_set :@real_tabs, real_tabs
> end
>
> Notice how it not only suppresses indentation; it is also inserting
> HTML comments into the buffer which will be visible to any higher-
> level template which encloses it.
>
> And finally, here is the patch to the push_script method that scans
> for these HTML comments and acts accordingly:
>
> diff --git a/vendor/plugins/haml/lib/haml/buffer.rb b/vendor/plugins/
> haml/lib/haml/buffer.rb
> index 4bdac1d..5e8638c 100644
> --- a/vendor/plugins/haml/lib/haml/buffer.rb
> +++ b/vendor/plugins/haml/lib/haml/buffer.rb
> @@ -78,8 +78,22 @@ module Haml
> @buffer << "\n"
> end
>
> - result = result.gsub(/^/m, tabs(tabulation))
> - @buffer << "#{result}\n"
> + tab = tabs(tabulation)
> + pre = false
> + result.each do |line|
> + case line
> + when /<!-- Haml: start pre -->/
> + pre = true
> + when /<!-- Haml: end pre -->/
> + pre = false
> + else
> + if pre
> + @buffer << "#{line}"
> + else
> + @buffer << "#{tab}#{line}"
> + end
> + end
> + end
>
> if close_tag
> @buffer << "#{tabs(tabulation-1)}</#{close_tag}>\n"
>
> Yes, it is a horrible hack, and probably quite slow, but it works. I'd
> still like to find a more elegant solution though. I can't think of a
> way to communicate this stuff back up into enclosing templates without
> embedding some kind of marker like that in the text.
>
> And on a side note, a minor bug found while inspect the code in that
> file:
>
> diff --git a/vendor/plugins/haml/lib/haml/buffer.rb b/vendor/plugins/
> haml/lib/haml/buffer.rb
> index 4bdac1d..5e8638c 100644
> --- a/vendor/plugins/haml/lib/haml/buffer.rb
> +++ b/vendor/plugins/haml/lib/haml/buffer.rb
> @@ -152,7 +166,7 @@ module Haml
> # Gets <tt>count</tt> tabs. Mostly for internal use.
> def tabs(count)
> tabs = count + @tabulation
> - ' ' * tabs
> + ' ' * tabs # BUG: <-- this line has no effect
> @@tab_cache[tabs] ||= ' ' * tabs
> end
>
> Note how the second line has no side effects so is really just wasting
> time. It effectively renders the optimization that that method tries
> to implement (avoiding the recalculation of the tab text) ineffective,
> because it recalculates it anyway and just throws it away.
>
> Cheers,
> Wincent
>
>
> >
>
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