[ python-Bugs-215126 ] Over restricted type checking on eval() function

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Bugs item #215126, was opened at 2000-09-22 15:36
Message generated for change (Comment added) made by mcherm
You can respond by visiting: 
https://sourceforge.net/tracker/?func=detail&atid=105470&aid=215126&group_id=5470

Category: Python Interpreter Core
Group: Feature Request
Status: Open
Resolution: Later
Priority: 5
Submitted By: Nobody/Anonymous (nobody)
Assigned to: Raymond Hettinger (rhettinger)
Summary: Over restricted type checking on eval() function

Initial Comment:
The built-in function eval() takes a string argument and a dictionary.  The second argument should allow any instance which defines __getitem__ as opposed to just dictionaries.

The following example creates a type error:
  eval, argument 2: expected dictionary,   instance found

class SpreadSheet:
    _cells = {}
    def __setitem__( self, key, formula ):
        self._cells[key] = formula
    def __getitem__( self, key ):
        return eval( self._cells[key], self )

ss = SpreadSheet()
ss['a1'] = '5'
ss['a2'] = 'a1*5'
ss['a2']


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Comment By: Michael Chermside (mcherm)
Date: 2003-12-16 10:37

Message:
Logged In: YES 
user_id=99874

I'll just add my voice as somebody who would find this to 
be "darn handy" if it could ever done without noticably 
impacting the speed of python code that DOESN'T use eval().

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Comment By: Tim Peters (tim_one)
Date: 2000-09-23 00:18

Message:
Added to PEP 42.

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Comment By: Tim Peters (tim_one)
Date: 2000-09-22 15:42

Message:
Changed Group to Feature Request.  Should be added to PEP 42 (I'll do that if nobody beats me to it).

CPython requires a genuine dict now for speed.  I believe JPython allows any mapping object.


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You can respond by visiting: 
https://sourceforge.net/tracker/?func=detail&atid=105470&aid=215126&group_id=5470