[Owncloud] Problems with the current template engine

[Thomas Müller]

Why the heck are we using PHP anyway? ;-)

/me hides


Am Dienstag, dem 09.10.2012 um 16:20 schrieb Victor Dubiniuk:
> Hi Bernhard,
> 
> I have a long experience with Smarty and tried a couple of other template
> engines. Most of them is nothing but PHP written in PHP.
> There are some brilliant exclusions like Slim and Haml in Ruby but both are
> not implemented in PHP completely.
> I consider phtml to be the best option for templates.  One can say it is
> weird for designers but any other non-HTML syntax is weird for designers
> either.
> It's just my humble opinion.  :)
> 
> ---
> Victor
> 
> On Tue, Oct 9, 2012 at 5:06 PM, Bernhard Posselt <nukeawhale at gmail.com>wrote:
> 
> > Hi guys,
> >
> > I've ran into multiple problems with the current template engine setup.
> >
> > * Lack of documenation:
> > Since these are only used by Owncloud, we have to maintain the
> > documentation on the template engine. Using a third party engine would
> > simplify documentation since we only would have to document how this is
> > built into Owncloud. Not to mention that there isnt actually any
> > documentation about the current templating engine at all from what Ive
> > found (http://api.owncloud.org/classes/OCP.Template.html)
> >
> > * Lack of template inheritance:
> > Currently we can only organize templates by splitting them into
> > different parts and including them in a Top-Down like fashion. Template
> > inheritance solves this kinds of problems (an example:
> >
> > https://docs.djangoproject.com/en/dev/topics/templates/#template-inheritance
> > )
> >
> > * Weird and unsafe XSS escaping:
> > Most important topic for me. We currently escape values when they're
> > assigned to a template like $tpl->assign('var', $var). If you dont want
> > to invoke the XSS protection on the variable, you use
> > $tpl->assign('var', $var, false) which is really weird and non obvious.
> > Also: What do we escape? IIRC variables and arrays, but what about
> > objects? We at the news app pass an array with objects to the template
> > layer. Are the properties escaped? If they are, this could lead to
> > potential weird behaviour, not to speak of the performance impact
> > (reflection). As you see, theres no sane way to do XSS escaping when
> > passing values to the template layer.
> >
> > The solution? Easy: escape the values when they are printed to the
> > template. Most template engines forbid you to use PHP in the templates
> > (which is a good decision) and provide their own print statements like
> > Django's {{ variable }} or Rail's <%= variable %>. All printed values
> > are automatically escaped by default! If you want to prevent escaping
> > you just use a filter like {{ var|safe }}. The word safe alone gets me
> > thinking: why is it called safe? What are the risks?
> >
> > * Allowing PHP code in templates:
> > This is not only a security problem stated by the previous point, but
> > also an invitation to code mess. Allowing PHP code in the template
> > tempts people to disregard the MVC principles (like for instance doing
> > database queries in the templates, we have that problem too, I admit),
> > which makes your templates really inflexible and really hard to change.
> > Everytime I try to clean up our templates or adjust them, I give up in
> > frustration because I'd have to adjust all templates, some of which are
> > generated in a recursive way and thus also very complicated to understand.
> >
> > Coming from Django I've looked at two similar engines:
> >
> > http://www.h2o-template.org/
> > http://twig.sensiolabs.org/
> >
> > Both have good documentation, Twig doesnt do autoescaping but theres a
> > block for that. I'm curious about other suggestions, and it would also
> > be fine if they could be reviewed from a security context.
> >
> > PS: Sorry for the long post, here's a potato
> > http://efr0702.files.wordpress.com/2012/03/potato-b.jpg
> >
> > Cheers
> >
> > Bernhard Posselt
> >
> > _______________________________________________
> > Owncloud mailing list
> > Owncloud at kde.org
> > https://mail.kde.org/mailman/listinfo/owncloud
> >