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Overview of Pointers

Quxlang has separate pointer types for one object and for a position in an element sequence.

  • An instance pointer, ->T, points to one object.
  • An array pointer, =>>T, points to a position in a sequence of objects.

MUT and CONST qualify access, as in MUT->I32 and CONST=>>BYTE.

Taking an address and dereferencing

Postfix <- takes an object's address. Postfix -> dereferences an instance pointer or array pointer:

VAR value I32 := 7;
VAR pointer ->I32 := value<-;

pointer-> := 9;
ASSERT(value == 9);

Pointers can be null. Test them before dereferencing:

VAR optional ->I32 := NULL;
ASSERT(optional!?);

optional := value<-;
IF (optional??)
{
  use(optional->);
}

Array pointers

array[& index] produces an array pointer. Arithmetic advances in elements:

VAR values [4]I32 :[10, 20, 30, 40];
VAR begin MUT=>>I32 := values[& 0];

ASSERT(begin-> == 10);
ASSERT((begin + (2 AS SZ))-> == 30);

Instance pointers do not support sequence arithmetic.

Reference

See the Pointers Reference for pointer qualification, nullability, indexing and arithmetic, VOID reinterpretation, procedure pointers, lifetime, and validity constraints.1

  1. A GC pointer, ~>T, is the pointer type used for garbage-collected objects on supported managed-runtime targets. It is not interchangeable with an instance pointer or array pointer. ↩