[Tutor] Converting string or list to sum

[Iain]

On Thursday 29 January 2004 19:41, Danny Yoo wrote:
> On Thu, 29 Jan 2004, Iain wrote:
> > If I have a sum as a string (e.g. '2+3') or in a list (e.g. [2,'+',3]),
> > how can I get the result of the sum?
>
> Hi Iain,
>
>
>
> If we had a function that takes three arguments:
>
>     calculate(left_hand_side, operator, right_hand_side)
>
>
> then we might be able to say something like:
>
> ###
>
> >>> calculate(2, '+', 3)
>
> 5
>
> >>> calculate(42, '-', 43)
>
> -1
> ###
>
>
> Is this the sort of thing that you're asking?
>
>
>
> Talk to you later!

Hi Danny,

I was hoping for something more generic, but that might do the trick with a 
bit of effort.

I'm trying to learn Tk and writing a little GUI calculator - doubtless very 
badly but never mind.  I've got it doing everything except the calculation.  
At the moment, the  buttons pressed go into a list, so if I want 22 + 10 I'll 
have a list that looks like [2,2,'+',1,0].  I want to get from that to the 
answer of 32, and have it generic enough to cope with any basic arithmetic 
calculation.

Of course, if this is just a terrible way to do it, perhaps someone can 
suggest a better one.

Iain.