[Tutor] Is there a way to store and later use comparison operators (<, <=, =, >=, >) ?

[boB Stepp]

On Wed, Apr 29, 2015 at 5:49 PM, Peter Otten <__peter__ at web.de> wrote:
> boB Stepp wrote:

>> So I have stumbled (With your gracious help!) into a legitimate use of
>> eval()?
>
> No. To expand on Marks hint here's how to do it without evil eval().
>
> import operator
>
> comps = {
>     "=": operator.eq,
>     "<": operator.lt,
>     ">": operator.gt,
>     # ...
> }
>
> def choose_compare(operator, value0, value1, pass_color, fail_color):
>     op = comps[operator]
>     if op(value0, value1):
>         return pass_color, True
>     else:
>         return fail_color, False
>
> print(choose_compare("=", 1, 1, "red", "blue"))
> print(choose_compare("<", 1, 2, "red", "blue"))
> print(choose_compare("<", 2, 1, "red", "blue"))
>
> Rule of thumb: when you think you need eval() you're wrong.

Thanks, Peter! The lure of eval() once more avoided...


-- 
boB