On Sat, 2004-04-10 at 18:27, Ellers wrote:

<div id="content"> <span nevow:data="display" nevow:render="xml"/> <span nevow:data="edit" nevow:render="xml"> <form>this is edit: more will go in here...</form> </span> http://mesozoic.geecs.org "Never let your sense of morals prevent you from doing what is right." -- Salvor Hardin, Isaac Asimov's _Foundation_

Alex Levy wrote:

On Sat, 2004-04-10 at 18:27, Ellers wrote:

...

<div id="content"> <span nevow:data="display" nevow:render="xml"/> <span nevow:data="edit" nevow:render="xml"> <form>this is edit: more will go in here...</form> </span> nevow:invisible tags instead. Those won't show up in the resulting HTML, which makes it "lighter". As I often need selective output, I have a very simple general-purpose renderer: def render_ifeq(self, context, data): if data != (context.tag.pattern or ''): return '' return context.tag If you have, for example, a data_state that returns as the current data a string which represents some kind of "state", you could code the template: <p> You are editing the object. </p> <p> Your changes have been saved. </p> <p> Your are just viewing the object. </p> This will emit a single one of the three <p>'s as appropriate. Several other similar approaches are possible, e.g., put the patterns on the tags among which you want to choose, and have the renderer examine all contained patterns and pick the right one[s]; generalize ifeq to an ifmatch that treats patterns as regular expressions; and so on, and so forth. I'm striving to avoid obscuring my stuff with excessive and unwarranted generality, and so far I've found the simple ifeq serves my purpose, so that's what I'm currently using. I _think_ (I could be wrong...) that using nevow:pattern as the "argument" to be used by data and render methods is quite consonant to nevow's design; there used to be some confusion, e.g. with the quondam nevow:key, but now that nevow:pattern is all that's left the approach appears to be to be simple and effective, allowing you to pick the right degree of generality. Alex