Question

This is a thought example of what I am thinking of:

test = 'x > 0';

while str2func(test)
   Do your thing
   x=x-1;
end

Is it possible to store whole logical operations in a variable like this?

Of course the str2func will break here. If it is possible this function will likely be something else. And I have only added apostrophes to the test variable content, because I cannot think of what else would be the storing method.

I can see it usefull when sending arguments to functions and alike. But mostly I’m just wondering, because I have never seen it done in any programming language before.

Answer 1

You can store the textual representation of a function in a variable and evaluate it, for example

test = 'x > 0';
eval(test)

should result in 1 or 0 depending on x’s value.

But you shouldn’t use eval for reasons too-often covered here on SO for me to bother repeating. You should instead become familiar with functions and function handles. For example

test =  @(x)x>0

makes test a handle to a function which tests whether its argument is greater than 0 or not.

Many languages which are interpreted at run-time, as opposed to compiled languages, have similar capabilities.