[Kss-devel] ree-stripout-comments branch

[Balazs Ree]

I created the ree-stripout-comment branch (should rather be called 
stripout-asserts) which is an experiment with the technology of creating 
a production and development version of the kss javascript.

We introduced the ;;; construct, if this appears in the beginning of a 
line, the line will appear only in the development version and not in the 
production version. The current code is marked this way and all logs, 
exception messages and a lot of the asserts during parsing and binding 
are now stripped. This results, in full compression mode, a 104K code 
size, and compared to the current 129K this means a 19% win at the first 
try. It may also be a bit faster, but I can't estimate this.

To use it with Plone, we need to again take the packing into our hands 
from RR. All things have to be set up manually, as I did not want to 
branch CMFPlone. 

This is how to try it:

1. switch kss.core to the branch ree-stripout-comments

2. In portal_javascript tool, rename ++resource++kukit-src.js to 
   ++resource++kukit.js, and enter the following condition into it:

    here/@@kss_devel_mode/isoff

3. create a new resource like the previous one, with the name  
   ++resource++kukit-devel.js with this condition:

    here/@@kss_devel_mode/ison

    or if you want, you can combine both of these conditions with the 
    current condition that disables kss for anonymous users, but this
    is not important for testing.

So these are the two resources we have, and which one gets into the page, 
is selected by the view.

It's all set up now. You can visit a simple UI at the browser page:

    @@kss_devel_mode/ui

That shows you if kss is currently in production or in development mode. 
You can toggle a browser cookie with the buttons. This is a client side 
setting, no need to change the server for switching to development mode: 
this is a very important principle imo. The setting can also be overruled 
by RR: if you set debug mode in portal_javascript, kss will get into 
development mode permanently and independently of the setting of the 
cookie.


Something about the technology.

The ;;; construct works reasonable well, but it has some artifacts. I am 
using the following patterns in the commentification:


   ;;; this line is only in development 


  This cannot be used however

  - inside expressions that span multiple lines (like () or a string +)

  - inside the switch statement

so I also used these:


       /*
   ;;; */
       this is only in development mode
       and this too
   ;;; /*
       */


and even these:


   ;;; /*
       this is only in production mode
       and this too
   ;;; */


Comments, suggestions? I am open for new ideas. I agree ;;; does not work 
so nice in some cases, but it's doable.

The stripout itself happens before the packer starts its job. This would 
stay so, even if this gets integrated to the packer, we will need two 
passes.

In the concatresource now you have the following packing levels available:

    - none:        the raw sources
    - devel:       like none but the ;;;-s themselves are removed
    - prod:        the production version unpacked, readable
    - safe-devel:  safe packing, devel version
    - safe:        safe packing of the production version
    - full-devel:  full packing, devel version
    - full:        full packing of the production version

Of these mostly devel, safe and full make sense. - At the moment only 
kss's concatresource can pack this way, RR can not yet.


Please try this branch and see if you can notice any difference in 
performance.

-- 
Balazs Ree