newline-handling problem in Sinatra's erb implementation

[RichMorin]

The Embedded Ruby implementation for Sinatra (1.4.7) removes (some) newlines. Basically, if an interpolated string is on a line by itself (no text either before or after), the newline goes away. The Ruby (2.0.0p481) ERB library does not exhibit this problem.

See https://gist.github.com/RichMorin/055bb69484207885ab51e7cdd6ac44dd for details.

-r

P.S. I tried posting this to the mailing list, but (like a post I made a couple of weeks ago) it was held for review. Hello?

[mwpastore]

Sinatra uses Tilt behind the scenes to dispatch calls to its render helper (and associated erb, haml, etc. helpers) to different rendering engines. When Tilt invokes ERB, it sets trim_mode to <> by default, which "omits newlines for lines starting with <% and ending in %>." Your call to ERB sets trim_mode to nil (by dint of your not including it in the call), so it doesn't trim anything.

This is the source of the inconsistency in your results. To align the results, you can either:

1. Set :trim to false in your call to erb (see here)
2. Set trim_mode to <> in your call to ERB.new
3. Use an alternate ERB implementation such as Erubis or Erubi

I'll defer the mailing list question to @zzak! I'm not sure if anyone is moderating it; last time I looked at it there had only been a handful of posts in the past year.

[RichMorin]

Thanks for clarifying the situation and suggesting alternatives.

[zzak]

Here is fine, I'm not sure anyone really uses the Mailing List anymore.

We also have slack.