[ZPT] Truncating strings

[Fred L. Drake, Jr.]

Ian Bicking writes:
 > <span tal:condition="python: len(var) > 10" tal:omit-tag="">
 >    <span tal:replace="python: var[:10]">var</span>...
 > </span>
 > <span tal:condition="python: len(var) < 10" tal:omit-tag="">
 >    <span tal:replace="var">var</span>
 > </span>

You can do this with less crud:

--------------------------------------------------------
<tal:block define="var     string:abcdefghijklmnop;
                   maxlen  python:10;
                   toolong python:len(var) &gt; maxlen;
                   partial python:var[:maxlen]">

  <span tal:replace="partial"
    /><tal:span condition="toolong">...</tal:span>

</tal:block>
--------------------------------------------------------

What changed:
- I used the tal: prefix on elements where you use tal:omit-tag="";
  this is really just a cosmetic difference.
- Except where I used tal:replace; using tal:replace is like using
  tal:content and tal:omit-tag="" at the same time.
- I kept all the python: expressions in one place, so it's easier to
  keep an eye on what's happening.
- I avoided re-computing any value; everything gets a name, no matter
  how short-lived.
- I encoded the > operator since an XML parser would scream about
  that, and I'm much more interested in the XML case.

Either approach can certainly be sliced and diced in a variety of
ways.

 > Well, that's not very appealing, is it?  Or a Python Script:

Your Python Script solution is really only available in Zope 2.

 > Really ZPT (TALES really) is painfully in need of easy-to-access 
 > formatters.  I saw discussions of it long ago in the archives, but is 
 > there any progress on this?  E.g.:

Evan has proposed an approach to bundling a handful of code with a
page template; that has some real merit.  I don't know what the
implementation status is.

Some work has been done on a branch to make it easier to support
formatting within path expressions, but that hasn't made it to the
trunk yet either.


  -Fred

-- 
Fred L. Drake, Jr.  <fred at zope.com>
PythonLabs at Zope Corporation