how to pass options to sub-template processor?

[sunaku]

Hello,

I use markdown: sub-templates inside my Slim templates. I was able to make Slim use Redcarpet for markdown processing via the Tilt API, as shown below. However, I don't know how to set default rendering options for Redcarpet, which is hidden somewhere in the Slim => Tilt pipeline. In particular, I want to enable GitHub-style code blocks and also use Albino/Pygments for syntax highlighting of code blocks.

I tried RTFM and browsing the Tilt & Temple source code, but no luck. So I ask you now for suggestions.

require 'slim'
Tilt.prefer Tilt::RedcarpetTemplate
# TODO: how to set rendering options on Redcarpet?
Slim::Template.new("bogus_file.md"){ "markdown:\n  ```ruby\n  puts \#{who}\n  ```\n" }.render(Object.new, :who => 123)

The above code yields:

"<p><code>ruby\nputs 123\n</code></p>\n"

But eventually (after I set my rendering options), I want to get something like this:

"<p><pre><code lang=\"ruby\">\n<strong>puts</strong> <span style="color: red">123</span>\n</code></pre></p>\n"

I'm using ruby 1.9.2p290 (2011-07-09 revision 32553) [x86_64-linux] with slim (1.0.3), tilt (1.3.3), and redcarpet (1.17.2).

Thanks for your consideration.

[minad]

@sunaku: Good point! There is currently no syntax to set options for embedded engines. Which option do you need to set? Do you have a syntax proposal?

[sunaku]

I want to set the following Redcarpet options:

        :no_intra_emphasis - do not parse emphasis inside of words.
            Strings such as `foo_bar_baz` will not generate `<em>`
            tags.

        :tables - parse tables, PHP-Markdown style

        :fenced_code_blocks - parse fenced code blocks, PHP-Markdown
            style .Blocks delimited with 3 or more `~` or backticks
            will be considered as code, without the need to be
            indented. An optional language name may be added at the
            end of the opening fence for the code block

        :autolink - parse links even when they are not enclosed in
            `<>` characters. Autolinks for the http, https and ftp
            protocols will be automatically detected. Email addresses
            are also handled, and http links without protocol, but
            starting with `www.`

        :space_after_headers - A space is always required between the
            hash at the beginning of a header and its name, e.g.
            `#this is my header` would not be a valid header.

I think the best place to set these would be when we tell Tilt our preferences:

Tilt.prefer Tilt::RedcarpetTemplate, my_options_hash

Thanks.

[sunaku]

I found a workaround to the issue. In fact, perhaps this is how Tilt is meant to be used:

>> require 'slim'
=> true
>> Tilt.prefer Class.new(Tilt::RedcarpetTemplate){ def options; {:fenced_code_blocks => true, :superscript => true, :smartypants => true, :no_intra_emphasis => true}; end }, 'markdown'
=> ["markdown"]
>> Slim::Template.new("bogus_file.slim"){ "markdown:\n  hello_world_this_is -- 2^(nd)\n  ```ruby\n  puts \#{who}; def foo; end\n  ```\n" }.render(Object.new, :who => 123)
=> "<p>hello_world_this_is &ndash; 2<sup>nd</sup>\n<code>ruby\nputs 123; def foo; end\n</code></p>\n"

This is using Redcarpet 2.0.0b5, by the way.

[judofyr]

Tilt's template engine lookup is separate from template initialization, so this is probably something that Slim should provide.

Camping solves this problem by having a per-app options-hash where you can set it:

Camping.goes :Foo
Foo.set :markdown, { :fenced_code_blocks => true }

Sinatra does the same.

[minad]

Fixed in master.

Slim::EmbeddedEngine.set_default_options :markdown => {:fenced_code_blocks => true}

This needs to be documented.

@judofyr: Any ideas how to make such things on a per app-basis, not on a per-ruby-instance basis? This is a Temple thing.

[sunaku]

Sorry for the late reply @minad but that snippet doesn't work:

## ruby 1.9.3p374 (2013-01-15 revision 38858) [x86_64-linux]
>> require 'slim'
true
>> Slim::VERSION
"1.3.6"
>> Slim::EmbeddedEngine.set_default_options :markdown => {:fenced_code_blocks => true}
{:markdown=>{:fenced_code_blocks=>true}}
>> Slim::Template.new("bogus_file.slim"){ "markdown:\n  hello_world_this_is -- 2^(nd)\n  ```ruby\n  puts \#{who}; def foo; end\n  ```\n" }.render(Object.new, :who => 123)
"<p>hello<em>world</em>this_is -- 2^(nd)\n<code>ruby\nputs 123; def foo; end\n</code></p>\n"

Could you please tell me how to make it work with Slim 1.3.6? 😅

[sunaku]

Never mind. I found the answer in issue #245. 😤

Tilt.prefer Tilt::RedcarpetTemplate::Redcarpet2, 'markdown'

By adding the above line, we ensure that Slim uses Redcarpet (for which the :fenced_code_blocks => true option is meant) like this:

>> require 'slim'
true
>> Slim::EmbeddedEngine.set_default_options :markdown => {:fenced_code_blocks => true}
{:markdown=>{:fenced_code_blocks=>true}}

## the problem (notice the <p><code> in the rendered output):

>> Slim::Template.new("bogus_file.slim"){ "markdown:\n  hello_world_this_is -- 2^(nd)\n\n  ```\n  puts \#{who}; def foo; end\n  ```\n" }.render(Object.new, :who => 123)
"<p>hello<em>world</em>this_is -- 2^(nd)</p>\n\n<p><code>\nputs 123; def foo; end\n</code></p>\n"

## the solution (notice the <p>\n\n<pre><code> in the rendered output):

>> Tilt.prefer Tilt::RedcarpetTemplate::Redcarpet2, 'markdown'
["markdown"]
>> Slim::Template.new("bogus_file.slim"){ "markdown:\n  hello_world_this_is -- 2^(nd)\n\n  ```\n  puts \#{who}; def foo; end\n  ```\n" }.render(Object.new, :who => 123)
"<p>hello<em>world</em>this_is -- 2^(nd)</p>\n\n<pre><code>puts 123; def foo; end\n</code></pre>\n"

Cheers!

[sunaku]

I learned recently that Redcarpet has_two_ sets of options. See my blog post for details and an updated solution. 🍰