A minimal alternative to ERB!

addis_a · August 27, 2013, 11:36am

Hi guys,

I have tried to understand how ERB works and I have designed my own
template engine : {% statement %} and {{ expression }}.

I want to share the code with you :

https://gist.github.com/astraction/6351299

Only 33 lines of code (Ruby is so powerful !) and it should be much
faster than ERB (but I haven’t done any benchmarks).

It’s mainly for learning purpose. Of course, there is much room for
improvement (caching the compiled code, helpers methods, feel free to
help me).

Sébastien

oria · August 27, 2013, 11:42am

On Tue, Aug 27, 2013 at 11:36 AM, Sbastien D.
[email protected]wrote:

faster than ERB (but I haven’t done any benchmarks).

It’s mainly for learning purpose. Of course, there is much room for
improvement (caching the compiled code, helpers methods, feel free to
help me).

Your regexes are flawed because they are too greedy:

irb(main):001:0> ‘{{a}}{{b}}’.scan(/{%(.+)%}|{{(.+)}}|([^{}]+)/)
=> [[nil, “a}}{{b”, nil]]

You should at least use reluctant quantifier:

irb(main):002:0> ‘{{a}}{{b}}’.scan(/{%(.+?)%}|{{(.+?)}}|([^{}]+?)/)
=> [[nil, “a”, nil], [nil, “b”, nil]]

Cheers

robert

oria · August 27, 2013, 11:49am

Eagle eye !

Thanks Robert ! I will fix that.

oria · August 27, 2013, 1:47pm

See the new code here :

https://gist.github.com/astraction/6352528

(Sorry, wrong move, I had to recreate a new gist repository.)

oria · August 27, 2013, 7:33pm

Neat way to grok parsing in ruby! Nice script. Thanks for sharing.

oria · August 27, 2013, 4:00pm

You have to know that exists others alternatives.
I prefer haml, is very powerful and fast.

oria · August 27, 2013, 8:47pm

On Tue, Aug 27, 2013 at 7:00 AM, Hari C. [email protected] wrote:

I prefer haml, is very powerful and fast.
GitHub - haml/haml: HTML Abstraction Markup Language - A Markup Haiku

Haml is anything but fast. It blows your method caches any time you
render
a template:

github.com/haml/haml

Refactoring if internals to not flush inline caches at runtime

haml:master ← dbussink:master

opened 02:20PM - 04 Jan 13 UTC

dbussink

+10 -9

First of all, I don't expect this pull request to merged, I intend it to start a… discussion since I'm not very familiar with the internals of Haml. It shows perhaps a way to start addressing the issue I'll explain further in this pull request. When benchmarking Haml with both Rubinius and JRuby, it was found that some of the patterns in Haml have a very detrimental effect on performance. Probably MRI also suffers from this, although in a lesser amount. The main issue here with the dynamic use of Object in https://github.com/haml/haml/blob/master/lib/haml/engine.rb#L122-L132. Every time Object#extend is called, it has to flush inline caches. This means also that JIT'ed code needs to be recompiled and never be properly optimized. Also the usage of dynamic instance variables is significantly slower than defining them beforehand. So in this case, an object that has an explicit accessor such as Haml::Scope in this pull request, which is for instance variables that are always used such as @haml_buffer beneficial. What I'm wondering here is, whether it would be possible in Haml to make the code more optimization friendly. That means using less runtime changes to object types when possible. Perhaps there are situations where this can't be done, but I imagine that there should be a large number of cases where this can be improved. For some benchmarks on the effect of Object#extend, also see here: http://tonyarcieri.com/dci-in-ruby-is-completely-broken. The biggest problem is that it doesn't affect code only locally. Especially in MRI, each Object#extend flushes all the inline caches for every method call in the system, which is a very severe performance penalty here.

oria · August 28, 2013, 9:06am

Hi,

On 27 Αυγ 2013, at 21:46 , Tony A. [email protected] wrote:

On Tue, Aug 27, 2013 at 7:00 AM, Hari C. [email protected] wrote:
I prefer haml, is very powerful and fast.
GitHub - haml/haml: HTML Abstraction Markup Language - A Markup Haiku

Haml is anything but fast. It blows your method caches any time you render a
template:

Refactoring if internals to not flush inline caches at runtime by dbussink · Pull Request #615 · haml/haml · GitHub

–
Tony A.

There are a dozen of similar projects to fast-type HTML:

slim: http://slim-lang.com
less: http://www.lesscss.org
liquid: http://liquidmarkup.org
markaby: http://markaby.github.io

and for CSS most notably:
SASS

Panagiotis (atmosx) Atmatzidis

email: [email protected]
URL: http://www.convalesco.org
GnuPG ID: 0x1A7BFEC5
gpg --keyserver pgp.mit.edu --recv-keys 1A7BFEC5

oria · September 1, 2013, 8:17pm

That’s a neat script, Sébastien! Thanks for sharing. Learned something
new today.