How to make a large array usable within a function with good performance

Question

I have a peace of precedural code which is executed in a loop. This peace of code requires one large array, but only for reading and not manipulating purposes. I generate this array once before the loop.

Now I would like to move this code into a function in order to use it again is some other script, but I don't know how to that in a clean way, but still having a good performance:

• Generating this large array every time in the function itself would be bad, since it is always the same array and creates unnecessary overhead.
• I dont want to use a global array, since this is bad practise
• I guess therefore it would be the best to pass it as a paremeter every time I call the function.

I don't like that last option too much either, because it clutters the argument list and I am not sure about the overhead caused through this. As I understand it the array would be copied every time - would it be a good idea to pass it by reference therefore (by using the & operator)?

Answer 1

Use OO-Programming, create a class with two methods, one for generating array and the second for the calculation using the array. Use patterns like Singleton to secure, that your object is the only instance or use static variables. Make a package to share this Class between different scripts/projects.

Since the question is very general is the answer to very abstract.

Answer 2

I guess passing it by refrence is good enough but sometimes generate time call pass by refrence warning.. Might cause you trouble later.

Answer 3

One, who is really concerned in performance, should

avoid processing large arrays in a performance-critical code.

instead of playing tricks of speeding up an essentially slow process.

So, without knowing a REAL CASE (the purpose, processing and content of the array) the only answer could be:

Thus, turn your array into a database and select only necessary data.

This is a general answer to such a general question like this.

Answer 4

You can serialize your array and write serialized in file. So it would be more fast to read that file, unserialize and use it later in your code.