Pass Python list to embedded Rust function

Question

I am learning how to embed Rust functions in Python, and everything works fine if my inputs are ints, but not list.

If my lib.rs file is:<

Answer 1

ctypes is about C bindings and in C there's no such a thing as a dynamic array.

The closest object you can pass to a C function is a pointer to integer that however is not a dynamic array because

1. It doesn't carry the size information
2. You cannot grow or shrink the area, just access existing elements

A simple alternative to passing pointers (and being very careful about not getting past the size) you could use instead is a function-based API.

For example:

getNumberOfThings() -> number
getThing(index) -> thing

but the Python code would then become like

def func():
    n = getNumberOfThings()
    return [getThing(i) for i in range(n)]

The counterpart (passing a variable number of elements) would be

def func2(L):
    setNumberOfThings(len(L))
    for i, x in enumerate(L):
        setThing(i, x)