evalstr

[Carel Fellinger]

Michael Chermside <mcherm at destiny.com> wrote:
>>>> class Eval:
> def __getitem__(self, key):
> 		return eval(key)

...

> Now THAT'S a wierd-but-cool hack! Very powerful and flexible, and
> simple enough to use. It should definitely be added to the cookbook. 
> It does, unfortunately, have one significant limitation: the expression
> cannot contain the character ")", which is one you'd like to use in
> expressions.

You can, but it has to match opening braces. The thing that is impossible
is to have strings inside the expression that have extra closing braces.

>>> "%((1+2)*(3+3))s" % Eval()
'18'
>>> "%('a'*2)s" % Eval()
'aa'
>>> "%('a)'*2)s" % Eval()
Traceback (innermost last):
  File "<stdin>", line 1, in ?
  File "<stdin>", line 3, in __getitem__
  File "<string>", line 1
    'a
    ^
SyntaxError: invalid token
>>>



-- 
groetjes, carel