limited python virtual machine

[Steven Bethard]

Alex Martelli wrote:
> Steven Bethard <steven.bethard at gmail.com> wrote:
>    ...
> 
>>If I could see how to go from 'object' (or 'int', 'str', 'file', etc.)
>>to 'eval' or '__import__', that would help out a lot...
> 
> 
>>>>object.__subclasses__()
> 
> [<type 'type'>, <type 'weakref'>, <type 'int'>, <type 'basestring'>,
> <type 'list'>, <type 'NoneType'>, <type 'NotImplementedType'>, <type
> 'module'>, <type 'zipimport.zipimporter'>, <type 'posix.stat_result'>,
> <type 'posix.statvfs_result'>, <type 'dict'>, <type 'function'>, <class
> 'site._Printer'>, <class 'site._Helper'>, <type 'set'>, <type 'file'>]
> 
> Traipse through these, find one class that has an unbound method, get
> that unbound method's func_globals, bingo.

Thanks for the help!  I'd played around with object.__subclasses__ for 
a while, but I hadn't realized that func_globals was what I should be 
looking for.

Here's one route to __builtins__:

py> string_Template = object.__subclasses__()[17]
py> builtins = string_Template.substitute.func_globals['__builtins__']
py> builtins['eval']
<built-in function eval>
py> builtins['__import__']
<built-in function __import__>

Steve