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§7.6. Reading and talking
A few actions apply not to items alone, but also involve what might be called conversation. The first is the one used for looking things up in books (which is conversation of a kind, even if the author is not present): "consulting ... about ...". For example,
In the Grove is a book of sybilline verses.
After consulting the book about "grove", say "The Grove is a sacred yadda, yadda. There's a tree, that sort of thing. Wisdom."
After consulting the book about "future events", say "It's a bit, what's the word? Delphic."
Note that what follows "about" here is a piece of text in double-quotes, and not the name of something. It can be almost any text at all, and in fact we shall later see (in the chapter on "Understanding") that we can match complicated patterns of words, too.
Similar actions are used for conversing with people:
After asking the Sybil about "verses", say "She blushes."
After telling the Sybil about "persians", say "She nods gravely."
After answering the Sybil that "I am mad", say "She sighs."
These would be produced by commands like "ask sybil about verses", "tell sybil about persians" and "answer i am mad". Answering is little-used except that it also catches commands like "sybil, something unrecognized", which inexperienced players sometimes type. Asking and telling, however, are important actions and the difference between them is often worth preserving. If you would prefer to make "tell sybil about X" do the same as "ask sybil about X", the following rule would serve:
Instead of telling the Sybil about something, try asking the Sybil about it.
Games with a lot of conversation often involve great heaps of rules like the ones above, which can be repetitious to type out. We shall also later see (in the chapter on "Tables") that we can tabulate questions and answers in a much more concise way, if we prefer.
See Topic columns for table-based ways to store and retrieve conversation
Sometimes we do not particularly want to deal with all the variations on asking, telling, or answering someone something, but want to direct everything to a single conversational command:
And similarly, a difference between GIVE and SHOW is sometimes overkill:
It is also often the case that we want to accept more than one form of a term. For instance
will match either "Darius" or "king". If necessary, we can go a step further and define our own token to match a variety of phrases, like this:
The token "[Greeks]" will match all of "Athenians", "Spartans", "Greeks", "hoplite army", or "hoplite forces". It will not match "hoplite" or "forces" alone; it is important to note that the / divides individual words which are understood equivalently, but does not define entire phrases as equivalent. More about how Inform understands specific phrases can be found in the chapter on Understanding.
Occasionally we will want to replace the player's question topic with another of our own devising. We can do this in the simplest possible case like so:
Note that this syntax did not work in older versions of Inform; it is now safe.
Inform already understands YES, NO, and SORRY as commands in their own right, which can make things a little sticky when we want a character to ask a question of the player. The most important thing is not to cover some of the possible phrasings while ignoring others.
The complexity arises from the fact that we want to handle both YES and SYBIL, YES. If we only had the latter, 'yes' would be treated as a text given to the Sybil, just as in the commands SAY YES TO SYBIL or ANSWER YES. But because we have defined it as a command (so that the player can use it independently), SYBIL, YES is understood as an order to the Sybil to do the YES action.
Fortunately, we can redirect everything, as here, so that the results wind up the same.
And if we want yet another variation not covered by the Inform standard:
But that is a matter for a later chapter.
Costa Rican Ornithology
The following relies on quite a number of features we haven't met yet: tables, rules for printing names, instructions for understanding the player's commands. It is offered simply as an example of how a fully implemented book might be handled in Inform.
With this "topic understood" phrase, we're telling Inform to print back the word or phrase that the player was attempting to look up. This overrides the more general default response, "You discover nothing of interest in the book."
We now have the essential elements to construct whatever books we like. Now let's have an example of a specific book:
We will come back to the idea of tables and table names later, but for now the important thing is that we have instructed Inform to look up its answers to consulting the bird guide in this form:
"[red]" or "[red] bird/macaw"
"You flip through the Guide for a while and eventually discover a reference to the [scarlet macaw], which appears to correspond with what you see before you."
"quetzal/trogon" or "resplendent trogon"
"The entry on the quetzal is quite lyrical, describing its brilliant plumage, flashing and igniting in the sunshine, which is supposedly sufficient to lure birdwatchers from all over the world. Unfortunately, the quetzal is described as being bright emerald in color, with a pink fuzz on its head and a long soft tail 'like a feather boa'. None of these describes your visitor."
The topic column is a bit special: it matches the player's input, and is not meant to be printed out again. Topic columns will be discussed further in the chapter on Tables. (Note also that, however it may appear in the documentation, the topic column should not be spanning multiple lines in our source text.)
We may also compress long or complicated topics by creating bracketed abbreviations, and in fact it's useful to do so now, to explain the red token we just used:
This technique is discussed further in the chapter on Understanding.
If we wanted more books, we could define those in the same way, giving each its own separate contents table to be used for consultation. But for the sake of the example we will keep it simple, and move on to the scenario itself: