On May 5, 12:11 am, Massimo Di Pierro <[email protected]> wrote:
> Less that two days ago Thadeus made a request:
>
> http://web2py.uservoice.com/forums/42577-general/suggestions/702804-b...
>
> for this to be supported in web2py:
>
> http://docs.djangoproject.com/en/dev/topics/templates/#template-inher...
>
> Today Thadeus sent me patch that implements it. It is a complete
> rewrite of the web2py template module with better comments, new
> functionality and - of course - backward compatible.
NOTE: Blocks are a general extension / inheritence point, and will
help write website templates, not only for layout but also for dynamic
adaptation.
In general, an "empty" block should be "just like" the old template:
{{ extends somefile.html}}
In taking a quick look at the code, it appears as if they've made
{{include}} from parent templates continue in backward
compatibility.
I also see a hint that an {{include}} could have an {{end}}, so I've
got some questions (maybe some test cases for the code will help clear
it up).
For example: with the keyword: {{block name}} ==> I would
expect that "inheritence" behavior is accomplished. That is, any
such block in a parent would be replaced by the same-named block in
the child (recursively). I believe this is what we have here.
What I'm less clear about, looking at this is 'extends'. It looks
like (and I expect) that {{extends}} will behave as it did before,
that is it will "replace" an empty, unnamed block (and for backward
compatability, this is the block aliased as {{include}} ).
What I _hope_ --- but am not clear about, is if 'extends' has also
been given the power of 'block', that is - if it is general: i.e.:
{{ [block | extends] blcok-name }}
such that {{ extends blockname }} will act like
blockname.append (and if blockname is a filename, will extend the
unnamed, or "plain include" block in the named file.
If not for backward compatibility, I think we do not need to refer to
filenames at all, as {{extends blockname}} is general, and for the
current behavior of "insertion" decays to extending an empty block.
I welcome multiple insertion points and block-override ("inheritence")
points.
I have one remaining question: currently the "parent" is named by
{{extends filename}} at the beginning of the child template.
With this change, how will that be handled? The "old" meaning of
extends was overloaded with 2 actions: name my parent, and
"override" (i.e. 'insert myself') the "empty" {{include}} block in my
parent.
The _more general_ version here (multiple extension points; multiple
inheritance-override points) extends seems like it's previous two
functions need to be split out.
Django, for example, uses "extends" to indicate "inherits from", but
that looses the opportunity to "piggy back" (extend) blocks. This
is a _great_ opportunity to go one better.
I would like to propose this addition:
[ ] REALLY do {{extends ...}} as I have suggested here; it is
symmetric, and I think will be useful (particularly when applying
"styles" to sites);
This will give us the template equivalent of a derived class _adding_
the parent class (e.g. initializer).
[ ] If the first {{}} template directive in a file is
{{ extends ...}} FOR BACKWARD COMPATIBILITY: assume the argument is
a filename, and process it as a deprecated version of this new
directive:
[ ] New Directive: {{ inherits filename}} --- to do what
"extends" does now in web2py (and django, I think), but says more
explicitly what the intended action is: it states a parent.
IF an {{include ....}} 'ed file inherits, should this be:
- valid composition (?), i.e., the "stylesheet" for a side menu
could be composed and applied this way in a component-like way.
- invalide (and assumed that the include-er should have included
the "parent"
If you think about user changeable styles, I think the first option
has clear appeal.
Thanks for this great direction guys. I hope these steps (and
perhaps my suggestions, after people think about, comment abou thtm)
will make for a truly orthogonal, skinnable templating package. I
went thru this rather quickly (and I am quite positively excited about
the change!), so I hope I didn't miss anything, misunderstand anything
- if I did, please correct.
Regards,
- Yarko
I'm just scanning through the code change, and it looks like they have
made "extends" general
>
> Please help us test it. Here you can get the latest trunk:
>
> http://web2py.com/examples/static/nightly/web2py_src.ziphttp://web2py.com/examples/static/nightly/web2py_osx.ziphttp://web2py.com/examples/static/nightly/web2py_win.zip
>
> Thank you. This is a big improvement.
>
> Massimo
