On 2 Nov, 14:06, Tino Wildenhain <[EMAIL PROTECTED]> wrote: > > An opposite approach to this form of dynamic HTML production is called > > push-style templating, as coined by Terence Parr: > > Hm. > > "<a href=$attr.url$>$attr.title$</a> > $if(attr.active)$ > $attr.submenu:menuItem()$ > $endif$" > > This looks ugly to me.
It also looks like an embedded mini-language to me. At any rate, I think making a 'push/pull' distinction misses the point. There are basically three approaches a templating system can use: 1. embed your control logic in your presentation markup, 2. embed your presentation markup in your control logic, or 3. keep the two separate and transform the presentation markup into some sort of DOM that can then be manipulated by the control code. What's significant here is the division of labour within the overall program. With the first two approaches, the templating engine handles both presentation and control (i.e. pretty much the entire View layer). The third approach only provides the presentation part, and does and says nothing about how the control part is implemented. So you can't really make a direct comparison of, say, Cheetah against PyMeld, as they don't cover the same amount of ground. Instead, you ought to consider how the entire View layer is put together in each case: - A Cheetah-based View is implemented as an HTML file with all of the required control code embedded in it. - A PyMeld-based View is implemented as an HTML file with id attributes that indicate which HTML elements should be converted into object model nodes, *plus* a Python module containing the control code that manipulates those nodes when rendering a finished document. Once you do compare like with like, the 'push/pull' distinction becomes somewhat irrelevant, as the control code for a PyMeld-based View could be pushing or it could be pulling. It's up to each program's developer to decide which way they want to do it - and in a proper MVC design it should always be pulling. ... A more useful distinction to make is between templating systems that combine appearance and control, and those that keep them separate, as this has significant implications when considering which type of templating system to choose, e.g.: - how complex the interface is, e.g. Cheetah's interface is larger and more complex than PyMeld's (even though they do the same thing), which means a longer learning curve - how clean the division of responsibility is, e.g. PyMeld separates HTML markup from Python code, which provides an obvious advantage if you've got a web designer handling one task and a Python programmer handling the other, or a likely disadvantage if both tasks are being handled by a relatively non-technical web designer - how abstract the program's View implementation is, e.g. a PyMeld- based View is more abstract than a Cheetah one, as markup and code are physically separate and are only combined in memory, which means the logic developer has to work harder in mentally modelling their View layer's structure and behaviour. HTH has -- Control AppleScriptable applications from Python, Ruby and ObjC: http://appscript.sourceforge.net -- http://mail.python.org/mailman/listinfo/python-list
