RE: [Zope] Use of lambda expression in DTML - Result!
Thanks for helping me solve this one. In the end I did the following:
1) hacked DocumentTemplate/DT_Util.py to include "filter" in the __builtins__
2) Installed PythonMethods and called pruneTree with parameter 'self' and content
return _.filter(
lambda x: x.getProperty('pruneFromTree',0)==0 ,
self.objectValues(['Folder'])
)
3) The new tag reads
dtml-tree name="Outline" leaves=dtcTemplate branches="pruneTree"
Chris McDonough wrote:
|If it's something you want badly (and if you haven't already) add it as
|a feature request to the Collector on Zope.org. Once other folks get
|past the knee-jerk reaction, maybe it'll sink in as a good thing. In
|the meantime, you can add it yourself if you like.
Good idea - I'll do that.
|Hopefully, you'll be so kind as to forgive me.
That's easy - as long as you keep writing HowTos of the same quality as "Zope
installation and upgrade" and "Zope enlightenment by understanding object
orientation"... :-)
|After seeing people post
|DTML code to the list that they need debugged that computes pay rates,
|has the shape of an arrowhead and scrolls past the maximum character
|length of my email client horizontally, I'm a little leery of adding
|anything whatsoever to DTML, as I think the rest of the folks at DC
|are. Reducing the complexity of DTML is a good thing, however
|it can be accomplished.
Agreed. You can do some very powerful things with the lamda expressions, but they
very quickly become unwieldy if used inappropriately, so I think people are right to
be wary. Having said that, any sort of block structured language has the same
pitfalls - e.g. Smalltalk, Self, even Java's anonymous classes could be used to
detrimental effect.
I prefer to leave this stuff to style and convention ("good practice") than prescribe
them entirely.
Thanks again,
Nick.
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[Zope] Use of lambda expression in DTML
I'm a newbie zopista, and python for that matter...
In brief: I get a NameError when invoking "filter(...)" from DTML. I thought this was
a built-in python method, so I'm a bit puzzled.
In detail:
1) I want to display a dtml-tree of my folder hierarchy, but I want to exclude all
Zwiki discussion groups.
2) In my index_html for the top level folder, I have the following:
dtml-tree Outline leaves=dtcTemplate
SPAN CLASS="tree"
dtml-if tree-item-expanded
dtml-if expr="objectValues(['Folder'])"
IMG SRC="dtml-var BASE2/Outline/OpenBook.gif" ALIGN="TOP" BORDER="0"
/dtml-if
STRONG
Idtml-var title/I
/STRONG
dtml-else
dtml-if expr="objectValues(['Folder'])"
IMG SRC="dtml-var BASE2/Outline/ClosedBook.gif" ALIGN="TOP" BORDER="0"
/dtml-if
dtml-var title
/dtml-if
/SPAN
/dtml-tree
which is cribbed straight from QuickStart.
3) I only want to ignore Zwiki groups, but they are out-of-the-box folders, so I can't
filter on meta-class.
4) My approach is just to add a property to the Zwiki folder ('blockTreeBranching')
5) In the dtml-tree tag, I change it to:
dtml-tree
Technical
leaves=dtcTemplate
branches_expr="filter( lambda f: not
f.hasProperty('blockTreeBranching', false), objectValues(['Folder']) )"
which, all things equal, should DoTheRightThang.
6) The code can be published, but when I view it, it spits out a NameError, choking on
"filter". Argh.
Ideas gratefully recieved...
Nick
HyperSpace Ltd,Birmingham Research Park, Edgbaston, UK, B15 2SQ
(e) [EMAIL PROTECTED] (t) +44 (0)121 414 7019
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