Supply condition in function call

[Joel Goldstick]

On Wed, Mar 25, 2015 at 1:51 PM, Manuel Graune <manuel.graune at koeln.de> wrote:
> Joel Goldstick <joel.goldstick at gmail.com> writes:
>
>> On Wed, Mar 25, 2015 at 1:29 PM, Manuel Graune <manuel.graune at koeln.de> wrote:
>>>
>>> def test1(a, b, condition="True"):
>>>     for i,j in zip(a,b):
>>>         c=i+j
>>>         if eval(condition):
>>>            print("Foo")
>>>
>> I'm not sure I understand your question, but condition will evaluate
>> to True or False regardless, so:
>>          if condition:
>>             print ("Foo")
>>          else:
>>             print ("Bar")
>>
>
> The point is (see examples below) to specify the condition that is to be
> evaluated when calling the function (as opposed to when stating the function).
>
>> eval can be dangerous as someone could put some unknown command with
>> side effects in condition
>>
>
> I know that. That's why I'm looking for an alternative. ;-)

Oh, now I see.  Do you know about this:
https://docs.python.org/2/library/ast.html#ast.literal_eval


>
>>> test1([0,1,2,3],[1,2,3,4],"i+j >4")
>>> print("Bar")
>>> test1([0,1,2,3],[1,2,3,4],"c >4")
>>> print("Bar")
>>> test1([0,1,2,3],[1,2,3,4],"a[i] >2")
>>>
>>> Resulting in
>>>
>>> Foo
>>> Foo
>>> Bar
>>> Foo
>>> Foo
>>> Bar
>>> Foo
>
> Regards,
>
> Manuel
>
> --
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> called panic. Neal Stephenson -- System of the world
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-- 
Joel Goldstick
http://joelgoldstick.com