[CherryPy] #1069: CherryPy dies if a config file value is a dictionary

[CherryPy]

#1069: CherryPy dies if a config file value is a dictionary
---------------------------+------------------------------------------------
Reporter: guest | Owner: fumanchu
Type: defect | Status: new
Priority: normal | Milestone:
Component: CherryPy code | Keywords:
---------------------------+------------------------------------------------
CherryPy allows — nay, requires — that config file values be Python
expressions. But if I try to provide a small dictionary that my
application needs:
{{{
[/]
selections = {'noller': 'bacon'}
}}}
then instead of parsing the dictionary, CherryPy returns:
{{{

Traceback (most recent call last):
File "/home/brandon/rover/cory/venv/bin/cherryd", line 108, in <module>
options.pidfile, options.imports, options.cgi)
File "/home/brandon/rover/cory/venv/bin/cherryd", line 19, in start
cherrypy.config.update(c)
File "/home/brandon/rover/cory/venv/lib/python2.7/site-
packages/cherrypy/_cpconfig.py", line 156, in update
reprconf.Config.update(self, config)
File "/home/brandon/rover/cory/venv/lib/python2.7/site-
packages/cherrypy/lib/reprconf.py", line 143, in update
config = Parser().dict_from_file(config)
File "/home/brandon/rover/cory/venv/lib/python2.7/site-
packages/cherrypy/lib/reprconf.py", line 214, in dict_from_file
return self.as_dict()
File "/home/brandon/rover/cory/venv/lib/python2.7/site-
packages/cherrypy/lib/reprconf.py", line 205, in as_dict
raise ValueError(msg, x.__class__.__name__, x.args)
ValueError: ('Config error in section: \'global\', option: \'selections\',
value: "{\'noller\': \'bacon\'}". Config values must be valid Python.',
'AssertionError', ())
}}}
It seems that the "assert" statement at transformer.py:1214 in the Python
2.7 standard library thinks that a dictionary node should start with a
"dictorsetmaker" but instead is seeing what it thinks is a "classdef"
node. Is this an error in the deprecated "compiler" Standard Library
package (I ran into one of those recently), or an error in how CherryPy is
calling it?

And, while all this is on the table: why does CherryPy bother with the
parser module and then trying to evaluate the (now deprecated) output,
instead of just running "eval()" on configuration file entries?

Thanks for any help in getting this working!

--
Ticket URL: <http://www.cherrypy.org/ticket/1069>
CherryPy <http://www.cherrypy.org>
CherryPy - a pythonic, object-oriented HTTP framework

[CherryPy]

#1069: CherryPy dies if a config file value is a dictionary
---------------------------+------------------------------------------------
Reporter: guest | Owner: fumanchu

Type: defect | Status: assigned
Priority: normal | Milestone: 3.2
Component: CherryPy code | Resolution:
Keywords: |
---------------------------+------------------------------------------------
Changes (by fumanchu):

* milestone: => 3.2
* status: new => assigned

Comment:

> And, while all this is on the table: why does CherryPy bother with the
parser module and then trying to evaluate the (now deprecated) output,
instead of just running "eval()" on configuration file entries?

Excellent question. If there are no objections, I'd be happy to switch to
using eval(), except for one feature. The current implementation is smart
enough to try to import expressions from named modules without requiring a
separate import statement. That would have to be re-implemented somehow in
an eval approach.

[CherryPy]

#1069: CherryPy dies if a config file value is a dictionary
---------------------------+------------------------------------------------
Reporter: guest | Owner: fumanchu

Type: defect | Status: assigned
Priority: normal | Milestone: 3.2
Component: CherryPy code | Resolution:
Keywords: |
---------------------------+------------------------------------------------

Comment (by guest):

Could you just wrap the eval statement in a try-except clause that catches
errors caused by undefined names, and then re-attempt the expression with
the name defined? (Because, of course, the name error might come from
inside of some function that the expression is calling, and not have to do
with the expression's namespace at all.)