id,summary,reporter,owner,description,type,status,priority,milestone,component,version,resolution,keywords,cc
541,i18n directive interferes with py:if expression,hoff.st@…,hodgestar,"I want to exclude a 'span' HTML element, if value=0. This is the minimized template markup for this use case:
{{{
<label i18n:msg=""timedelta"">
  Duration:
  <input type=""text"" name=""input""
         value=""$value"" />
  seconds
  <span py:if=""value"">
    (${fmt_value(value)})
  </span>
</label>
}}}
I've added the `i18n` directive to get a msgid like
 'Duration: [1:] seconds [2:](%(timedelta)s[3:]'
instead of split msgids 'Duration:', 'seconds', ...).

But with value=0 the `py:if` directive seems ineffective:
{{{
<label>Duration:
  <input type=""text"" name=""input"" value=""0"" />
  seconds
  <span>
    ()
  </span></label>
}}}
The 'span' element is included regardless of the value of 'value'.

Simply removing the `i18n` directive like
{{{
<label>
  Duration:
  <input type=""text"" name=""input""
         value=""$value"" />
  seconds
  <span py:if=""value"">
    (${fmt_value(value)})
  </span>
</label>
}}}
fixes this:
{{{
<label>Duration:
  <input type=""text"" name=""input"" value=""0"" />
  seconds
</label>
}}}
'span' disappears correctly, if value=0. If not for the braces I wouldn't have noticed this nor would I care.

Maybe there is a related issue in the Internationalization domain: When the `py:if` directive would strip the 'span' element successfully, the expression `i18n:msg=""timedelta""` would become invalid. Not sure, if that would hurt on template rendering time.",defect,closed,minor,0.7,Template processing,0.6,fixed,i18n,