On Tue, Jul 29, 2003 at 04:43:21PM -0400, Shane Hathaway wrote:
> Python expressions won't be banned. I will never consider them
> discouraged for all cases, either. There will always be a need for
> constructs like:
> <div tal:condition="python: a == b">...</div>
> <div tal:condition="python: (a and b) or c">...</div>
> However, the following is quite bad:
And quite common :-) Browse through some of the CMF skins...
> <tal:x define="ss nocall:modules/Products/PythonScripts/standard">
> <a tal:attributes="href python: ss.url_quote(some_url)" />
> This is un-Pythonic in numerous ways.
> - You can't use the import statement. In fact, you can't use any
> statements at all--only expressions.
> - The nocall: prefix.
> - The name 'modules' is present automatically along with many other
> names that aren't in the Python builtins namespace.
> - Importing using a path expression.
agreed on all 4. although, "import" is the only time I miss statements.
> - Binding a variable to a value without an equal sign.
That took some getting used to. I don't know why this was
chosen, but it seems a bit late to change it now.
> - You have to prefix Python expressions with "python:".
That's a feature! If we didn't have that, how would you know the
> Zope 2's method of slightly simplifying this is to write a two-line
> script and find it through implicit acquisition. The overhead of
> invoking a script is somewhat large, but here's what the template would
> look like anyway.
> <a tal:attributes="href python: here.url_quote(some_url)" />
yes, this is about the best you can do currently. In fact,
I quite like it. :)
> Zope 3 will not have implicit acquisition. In fact, no system but Zope
> 2 has implicit acquisition. That leaves us with no possible way to
> write the above statement in non-implicit Python! No matter what you
> do, you need some help from another kind of expression. Until recently,
> here was the way to write it in Zope 3.
> <tal:x define="url_quote nocall:here/++acquire++url_quote">
> <a tal:attributes="href python: url_quote(some_url)" />
> That alternative is just as complicated and un-Pythonic as importing a
> module in a template. I can't think of a better way to write this given
> the limitations of Zope 2 ZPT, without the giant implicit acquisition
> band-aid. Can you?
> Zope 3's new alternative looks about like this:
> <a tal:attributes="href here/format:url_quote" />
Where do you put the argument? I don't see some_url.
> To me, that's a vast improvment, and it's only one example.
It also raises some new questions that are about
on par with what would be needed to understand the zope 2 version:
What kind of thingie is "format:"? Where can I find it if I want
to learn what else it can do? What do I do if I want
format:some_custom_format? How could I replace or augment
the format thingie and not break any template that uses it?
Not that it's bad to raise these questions ... I just want to point
out that the answers are far from self-evident.
> You know what was actually wrong with DTML? The lack of Python Scripts.
> Without Python Scripts, everyone used DTML as a programming language.
> Once Python Scripts came around, DTML became a reasonable templating
> language again. If DTML used TALES expressions, it would be just as
> clean as ZPT.
I think I just said this in another post :)
Look! Up in the sky! It's MUZZY ANTIDISESTABLISHMENTARIANISTIC FJUKER!
(random hero from isometric.spaceninja.com)
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