Paul Winkler wrote:
1) It's surprising - other attributes don't behave this way.
Not very. The attributes it applies to need this, and I think it only happens if the content type of the ZPT is text/html. Try doing a checkbox withotu this feature ;-)
2) It's undocumented AFAICT.
Hmm... try the Zope 2.6 Book, I know I've read this documentation in the language specs somewhere...
3) It's specific to XHTML and likely to be problematic when using ZPT to generate other flavors of XML. I notice that this special behavior is applied regardless of what tag you put these attributes in.
See note about content type above.
There is of course the common idiom of writing the entire tag twice with two opposing "tal:condition"s, but that often leads to redundant html as well as redundant tag contents.
Erg! Ug! Yuk! People do this?!
<input type="checkbox" tal:conditional_attributes="checked request/some_var | nothing" />
I suspect that will work as expected if you remove the conditional_ prefix... do let me know though! cheers, Chris