Question

I’m trying to put buttons that have operators on them, like / * +, etc. I want to store the operator in such a way that I can use it in an expression, like 1 var 2 = 8

I would like to avoid having to use a different method for each operator, so an operator var would be my best option, I think. Objective-C for iPhone

Answer 1

The usual OO way to do this is to create a class “mathOperator” that has a method “performOp” taking two parameters, then inherit different classes from it that represent the different operations. I’m not an expert in objective-C, so my syntax is probably a bit off, but I think you’d write something like:

result = [var On:arg1 And:arg2];

for example

result = [var On:2 And:3];

would set result to 5 or 6 depending on whether var was set to add or mul. The implementation would look like (again, very roughly):

@interface Add: mathOperator
-(int)On: (int)arg1 And: (int)arg2;
@end

...

@implementation Add
-(int)On:  (int)arg1 And: (int)arg2 {
    return arg1 + arg2;
}

and of course similar for the other operators:

@implementation Mul
-(int)On:  (int)arg1 And: (int)arg2 {
    return arg1 * arg2;
}