[Python-Dev] Re: Update PEP 292

[Clark C. Evans]

On Thu, Aug 19, 2004 at 07:22:09PM -0400, Raymond Hettinger wrote:
|     IDLE 1.1a2      
|     >>> from Cheetah.Template import Template
|     >>> t = Template('the $rank is $@ a $$ dead ${rank}! $')
|     >>> t.rank='king'
|     >>> print t
|     the king is $@ a $$ dead king! $

I second this behavior.  Besides the missing 's', the second most common
error is not escaping the %, for example, <table width="100%"> is
painful, especially when you go through two or three stages of
substitution.  The behavior of Cheetah reflects real-world experience.
Most of the time your templates are edited by HTML monkeys or people
writing form letters or help screens.   If a substitution fails, it will
be obvious. This is one case where being explict causes more problems
than it fixes.

I've found Cheetah's implementation to be quite useful and would hope
that any 'standard' template mechanism would be advised by the good work
Chuck Esterbrook and Mike Orr.  The other mechanism I like is the dotted
notation to traverse objects.

Also, I really like Cheetah's mechanism where the template object
doubles as a dictionary of values.  In particular, it would be nice to
put default values, during substitution, it would first look in the
dictionary applied via the % operator.  If a key is not found in the
applied dictionary, it would use the values given by the template
itself.   And, if cast to a string, it would only use the template's key
values.  If this feature was implemented, it'd be great to use keyword
arguments as default mapping values.   

  >>> t = Template("$foo $bar $bing",foo='wibbles',bar='womble')
  >>> print t
  wibbles womble $bing
  >>> print t % {'bar': 'bingles'}
  wibbles bingles $bing
  >>> t.bing = 'wicken'
  >>> t
  wibbles womble wicken

Cheers,

Clark