[ZPT] Deafening chirping of crickets

Evan Simpson evan at 4-am.com
Fri Apr 18 16:30:27 EDT 2003

Evan Simpson wrote:
> It will, of course, be much more common to do simple 2- or 3-way choices 
> within a single group.

...and after reading Jaime's posting, I should really reiterate what 
this common case is, and looks like.

In Python:

  if A:
      do A stuff
  elif B:
      do B stuff
      do something else


  <div tal:condition-group="g1">
      <span tal:condition="g1 A">do A stuff</span>
      <span tal:condition="g1 B">do B stuff</span>
      <span tal:condition="g1 default">do something else</span>

Without condition-group, the TAL might need to be written:

  <span tal:condition="A">do A stuff</span>
  <span tal:condition="python:not A and B">do B stuff</span>
  <span tal:condition="python:not A and not B">do something else</span>

...depending on the logical relationship of A and B.  Unless we 
precompute A and B, we're also going to be doing duplicate calculations, 
slowing things down.


Evan @ 4-am

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