As a followup to **How to sort dynamically allocated wordlists -- Sorting UncheckedArray type**
(<https://forum.nim-lang.org/t/12312>): I am trying to use **UncheckedArray** types to support dynamic runtime dimensionality for **arrays** to avoid the overhead of **seqs**. How do I avoid the referenced runtime error below.?: * **-d:nimNoLentIterators** compile switch doesn't help :-( * naïvely using **ref var openArray[string]** just compile errors** import algorithm # Allocate a dynamic integer array of size n proc createUncheckedArray[T](n: int): ptr UncheckedArray[T] = cast[ptr UncheckedArray[T]](cast[pointer](alloc(n * sizeof(T)))) # Syntactic sugar template withLength*(elements: untyped, length: int): untyped = toOpenArray(elements, 0, length - 1) proc init_0_to_len*(elements: var openArray[int]) = for i in 0 .. elements.high: elements[i] = i # Generate a reordering vector to be used to place elements of associated arrays in sorted order template newOrder*() {.dirty.} = var length = elements.len index = createUncheckedArray[int](length) init_0_to_len index.withLength length # When MAKE_FAIL enabled the following generates the runtime error: # # Error: 'elements' is of type <var openArray[string]> which cannot # be captured as it would violate memory safety... # using '-d:nimNoLentIterators' helps in some cases. # Consider using a <ref var openArray[string]> which can be captured. (index.with_length length).sort do (a, b: int) -> int: elements[a].cmp elements[b] echo "newOrder: ", index.withLength length discard index # Using hardwired dimensionality -- works fine proc newOrder1*[T](elements: array[4, T]) = newOrder # Same as above but want to accept variable length element array proc newOrder2*[T](elements: var openArray[T]) = neworder when isMainModule: const MAKE_FAIL = false var words = ["aaa", "ddd", "ccc", "bbb"] integers = [1, 4, 3, 2] stdout.write "neworder1 string: "; newOrder1[string](words) Run
