Address of a variable: Difference between revisions

=={{header|Quackery}}==

Quackery does not have variables, and its memory model is based on dynamic arrays ("nests" in Quackery parlance) rather than a single continuous block of RAM, so, for example, an entry on the return stack has two parts; a pointer to a nest and a numerical offset into the nest (i.e. the location of an item within the nest) If the offset is non-negative, the offset is from the (zero-based) start of the nest, and if the offset is negative it is from the end of the nest, with the last item in the nest being at position -1.

The word <code>peek</code> returns a item located within a nest, given a nest and an offset.

The word <code>poke</code> takes a Quackery object, a nest, and an offset as arguments and returns a new nest, similar to the argument nest, except with the contents of the offset location replaced by the specified object. (Nests are immutable except under specific circumstances.)

Illustrating this as a dialogue in the shell (the Quackery REPL.)

<pre>/O> [ 10 11 12 13 14 ] is mynest ( create a named nest containing numbers )

... ' mynest 2 peek echo ( print the content of item #2 in mynest )

...

12

Stack empty.

/O> 99999 ' mynest 2 poke echo ( replace 12 with 99999 and print result )

...

[ 10 11 99999 13 14 ]

Stack empty.</pre>

<code>quid</code> returns a numerical value associated with an object in Quackery. See the discussion of <code>id()</code> in the [[Address of a variable#Python|Python entry]]. Quackery is implemented in Python, and <code>quid</code> in Quackery is equivalent to <code>id()</code> in Python.