| Chapter 12: Advanced Actions |

| 12.1. A recap of actions

Actions are impulses to do something, which arise sometimes through typed commands:

> >examine tapestry

and sometimes through "try" phrases occurring in other rules:

> Before examining the tapestry, try switching the ultraviolet light on.

Every action either succeeds or fails, though failure may not be a bad thing (something better may have happened). Besides any rules applied in the source text, actions are subject to basic realism rules. A general rule ensures that actions are rejected if the actor would need to touch something which is out of reach, or see something which is invisible; and a couple of hundred other built-in rules police individual actions. For instance, if the ACTIONS testing command has been used to switch monitoring on, then:

> >unlock cage with watermelon
> [unlocking cage with watermelon]
> That doesn't seem to fit the lock.
> [unlocking cage with watermelon - failed the can't unlock without the correct key rule]

Actions generated by "try" phrases are allowed to run "silently", which means that if nothing out of the way happens and they succeed, then nothing is printed. For instance:

> Before examining the tapestry: say "(Switching on the lamp first.)"; silently try switching the ultraviolet light on.

There are many ways to impose extra rules on actions, and we have seen three main kinds: Before rules, intended so that preliminary activities like the one above can happen before the action is tried; Instead rules, which block or divert the intention, or may cause something spectacularly different to happen; and After rules, which allow for unexpected consequences after the action has taken place.

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