operators from strings?

Game Engine Game Engine Support and Discussion
1

Is there a way to convert operators from strings? I’m doing a big overhaul of my dialogue/quest system and making it more robust, but I am having trouble finding anything on this…the more research I do the more I just see string comparison but nothing in regards to converting strings to operators…

for example I return a list from a txt, ini whatever into a list called…we’ll say lines[].
I have a string line[0] that I split into it’s own list I’ll call it compare…
so…
compare = line[0].split(’:’)
It returns [gameObject,property,operator,value]…by operator I mean comparison… >,<, != etc…

is this possible to do simply? or do I need to just get stupid and roll my own hacky solution? by hacky I do not mean buggy…I just mean not optimized or pythonic(so to say)…like assigning a number and doing a lookup with a switch…but this could get messy.

I do understand the security risks.

EDIT: I think I have found something…finally I stumbled upon the operator lib…now I just need to see if I can get it to work.

2

You can address the operators using the getattribute function and some magic names (you can use dir(obj) to see what they all are). This means if you have a dict mapping symbols to these magic names, and then a call to getattribute to retrieve the function, you can do it in quite a small amount of code:


OPERATORS = {
    '=': '__eq__', 
    '!=': '__ne__', 
    '+': '__add__',
    '-': '__sub__',
    '&gt;': '__gt__', # I may have this the wrong way around.
    ....
}


...
operand_a = &lt;the thing you are operating on&gt;
operand_b = &lt;the other thing you are operating with&gt;
str_operator = &lt;something like +, &gt; != etc &gt;
result = operand_a.__getattribute__(OPERATORS[str_operator])(operand_b)

So it could be:


prop_val = gameObject[property]
new_prop_val = prop_val.__getattribute__(OPERATORS[operator])(value)
gameObject[property] = new_prop_val
3

Thanks,I managed to get it working…but I did not define a dict…I simply assign them based on a string value in a small function from reading and parsing the text file…the script only triggers once during a key press(action button for speaking to characters and if I click on a button) so it’s a little longer(more lines) but it is simpler to read for others or me…which helps if I have to come back to it…again ugh! :slight_smile: