[Twisted-web] handling rendering exceptions: patterns strategy?

[Federico Tomassini]

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Hi,

I'm trying to create a machinery to handle renderer exceptions.

Considere the following template:

 <span nevow:render="main_page">

   <span nevow:pattern="main_pattern">
    ...
   </span>

   <span nevow:pattern="safe_pattern">
    <span nevow:render="handle_err">Oops, there was an exception</span>
   </span>

 </span>


The idea is to define a base class so that, for each page based on such
template, on renderer exceptions, the main pattern is deleted and the
failsafe pattern is filled with a human readable error.

For example:

class basePage(rend.Page):

  def render_main_page(self, ctx, d):
    try:
     render_the_main_pattern(...)

    except Exception, err:
     self.strexception= str(err)
     render_the_safe_pattern(...)


  def render_handle_err(self, ctx, d):
    if hasattr(self, 'strexception'):
     return self.strexception
    return 'UfoError'

class OtherPage(basePage):
  ...


It would be very nice to have such machinery: how can I choose to render
the safe_pattern if and only if the main pattern rendering fails?

Otherwise, is there in your opinion a better strategy?

- --
efphe
Today is Setting Orange, the 55th day of Chaos in the YOLD 3174
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