Chapter 20: Lists
20.6. Lists of objects

While there are lists for any kind of value, the form that is useful most often is "list of objects". There is nothing really different about this:

let L be {the pot plant, the foxglove};

makes a list of two objects as usual. However, a much faster and more systematic way to build lists of objects is to use descriptions. If D is any description then "the list of D" produces a list of all the objects matching D. For instance:

let L be the list of open containers;
add the list of open doors to L;

means that L now contains the open containers (if any) followed by the open doors (if any). Or, for example:

let L be the list of things;
remove the list of backdrops from L;

makes a list of all non-backdrops.

As mentioned above, lists of objects can be said in two additional ways:

"[L with definite articles]"
"[L with indefinite articles]"

And as mentioned below, they can be sorted in property value order:

sort L in P order;
sort L in reverse P order;

where P is any value property. In all other respects, lists of objects are no different to other lists.


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* Example  What Makes You Tick
Building a fishing pole from several component parts that the player might put together in any order.

RB


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