Delicious, Delicious Rocks

Example 196

★★★

Adding a "sanity-check" stage to decide whether an action makes any sense, which occurs before any before rules, implicit taking, or check rules.

In some cases, we may want to add new stages to action processing. One possibility is a stage where we check the sanity of what the player is trying to do before executing any of the other commands; so that we avoid, for instance

>EAT ROCK
(first taking the rock)
That's plainly inedible.

Here is how we might insert such a stage in our action processing, using rulebook manipulation.

Play/modify in Borogove

Play in Quixe

"Delicious, Delicious Rocks"

Section 1 - Procedure

The sanity-check rules are a rulebook.

This is the sanity-check stage rule:

abide by the sanity-check rules.

The sanity-check stage rule is listed after the before stage rule in the action-processing rules.

Section 2 - Scenario

Candyland is a room. The lollipop tree is an edible thing in Candyland. The genuine rock is a thing in Candyland.

Sanity-check eating an inedible thing:

say "Your digestion is so delicate -- you're sure [the noun] wouldn't agree with you." instead.

Test me with "eat lollipop / eat rock".

Candyland
You can see a lollipop tree and a genuine rock here.

>(Testing.)

>[1] eat lollipop
(first taking the lollipop tree)
You eat the lollipop tree. Not bad.

>[2] eat rock
Your digestion is so delicate -- you're sure the genuine rock wouldn't agree with you.

Notice that now Inform does not try taking the rock before rejecting the player's attempt to eat it.

It is of course possible to get the same effect with

Before eating an inedible thing:
   say "Your digestion is so delicate -- you're sure [the noun] wouldn't agree with you." instead.

…and in a small game with few rules, there's not much reason to add an extra stage. The ability to modify the stages of action processing becomes useful when we have a fairly large game with sophisticated modeling and want to be sure that some kinds of message (such as the sanity-check) are always handled before other things that we might be doing at the before stage (such as generating implicit actions like opening doors before going through them).