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Arrays

The Arrays group contains the embedded script-runtime operations for reading and changing array length, plus Velox helpers that copy strings between dynamic arrays and TStrings collections.

Use the length functions to create or resize a dynamic array before assigning indexed elements. Use the collection helpers when a Velox or Delphi object exposes a TStrings-compatible list but the mapping needs a TStringArray, or the reverse.

Common tasks​

  • Use GetArrayLength to read the number of elements in a static or dynamic array.
  • Use SetArrayLength to allocate, grow, shrink or clear a dynamic array.
  • Use StringsToArray to take a value-only snapshot of a TStrings collection.
  • Use AddStringArrayToStrings to append array elements to an existing TStringList without clearing it.

Important behaviour​

Array indexes are zero based. A length of N provides indexes from 0 through N - 1. Resizing preserves the common prefix, initialises new elements, and finalises elements removed from managed arrays.

The conversion helpers copy string values. They do not transfer ownership of the source collection, copy its associated Objects, or synchronise concurrent access.

Edge cases and quirks​

  • GetArrayLength supports static and dynamic arrays, but SetArrayLength resizes only dynamic arrays.
  • The effective Velox calls take parameters even though the generated declarations in the index omit them: GetArrayLength(Arr) and SetArrayLength(Arr, Count).
  • In the shipped PascalScript runtime, a negative new array length is coerced to zero.
  • Velox's SetArrayLength changes one dimension per call and does not expose the broader string or multidimensional forms documented for Delphi and Free Pascal SetLength.
  • Collection arguments must refer to live objects. The helpers do not check for nil before dereferencing them.

External references​