In Lua, you can define a function at runtime using the loadstring() function, which takes a string of code as input and returns a function. Here's an example:
-- define a string of Lua code as a variable
local code = "function add(a, b) return a + b end"
-- load the code and execute it to define the function
local addFunc = loadstring(code)()
-- use the function
print(addFunc(3, 4)) -- output: 7
In the example above, we define a string of code that defines a function add() that takes two arguments and returns their sum. We then use the loadstring() function to load the code as a function, and execute it to define addFunc. We can then use addFunc as a regular Lua function.
Another way to define a function at runtime is to use anonymous functions, like this:
-- define an anonymous function and assign it to a variable
local addFunc = function(a, b) return a + b end
-- use the function
print(addFunc(3, 4)) -- output: 7
In this example, we define a function addFunc as an anonymous function, by assigning a function that takes two arguments and returns their sum to a variable. We can then use addFunc just like any other Lua function.