§4.9. Using new kinds of value in properties
It turns out to be very useful to create a new kind of value, and then create a property to hold it. So useful, in fact, that Inform provides two shortened forms for doing so. Here is the first, and the second (making "conditions") is in the section following.
Suppose we go back to our example of the candle lantern whose brightness we have to measure. It's clear that what we want to do is to define:
Brightness is a kind of value. The brightnesses are guttering, weak, radiant and blazing.
And now we can use the technique of the previous section:
The lantern has a brightness called the flame strength. The flame strength of the lantern is blazing.
This works very nicely. The "flame strength" property is now only allowed to have one of four values we allowed: guttering light, weak light, radiant light or blazing light. So we have succeeded in recording our measurement.
But it seems artificial to call the brightness of the lantern "flame strength", when we could instead simply call it "brightness". Much simpler to write:
The lantern has a brightness. The lantern is blazing.
Now "brightness" is the name of both the property and the kind of value. What's particularly nice is that we can now use the names of the possible brightnesses - "weak", "blazing" and so on - as adjectives. Inform knows that "The lantern is blazing" must be talking about the brightness property, because "blazing" is a brightness.
Now we can improve our dead ends:
A dead end is a kind of room with printed name "Dead End" and description "This is a dead end, where crags in the uneven rock are caught by the [brightness of the lantern] flame you hold aloft. Despite [river sound] there is no sign of the stream." A dead end is usually dark.
The "[brightness of the lantern]" is printed not as literal text, but as whatever the brightness currently is. (The square brackets mark it as what is called a text substitution, which will be the subject of the next chapter.) So we get something like this:
This is a dead end, where crags in the uneven rock are caught by the blazing flame you hold aloft. Despite a faint whispering of running water there is no sign of the stream.
So now we have a lantern, which has a brightness as a property. But we can build on this further if we like. A brightness such as "guttering" is a value, so it can have properties in its own right. That can be quite useful, in fact:
A brightness can be adequate or inadequate. A brightness is usually adequate. Guttering is inadequate.
This is convenient because it divides up the brightnesses:
The player carries a book. The description of the book is "[if the brightness of the lantern is adequate]Many secrets are now yours.[otherwise]No, the print's too tiny by this awful light."
And while we're at it, let's give each brightness its own corresponding temperature:
Temperature is a kind of value. 100C specifies a temperature.
A brightness has a temperature. The temperature of a brightness is usually 700C. The temperature of blazing is 1400C. The temperature of radiant is 1100C.
The description of the lantern is "The lantern shines with a flame at [temperature of the brightness of the lantern]."
(Candle flames are hotter than most people think.)
See Text with substitutions for more on varying what is printed
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Suppose we have an extremely detailed world model in which every object is characterized by many features -- in this example, material and height, though one could add more. Suppose further that we would like to generate descriptions of these things automatically for the most part, drawing the player's attention only to those aspects of the object that are particularly interesting.
So far, we have generally dealt with cases where the property of a thing can be a number (such as 3), a value (such as brightness), or a unit (like height, here). It is also possible for a thing to have a property which names another thing, as in "The mother of the baby trout is the large trout" -- where "mother" is a property, and its value, in the case of the baby trout, is large trout. We would define such a property with a line such as "A fish has a thing called the mother." In practice, though, this is a bit confusing as syntax; moreover, Inform has a much more powerful construct for talking about the ways in which one object relates to another object. A full discussion of this will have to wait for the chapter on Relations. For now, it is enough to say that we can do this:
This will allow us to declare that some objects imitate other objects, like so:
Now each of these types has one ideal representative which has the fundamental attributes of its kind: the ordinary chair is the most chairlike chair imaginable, the ordinary table is the epitome of tableness, and so on. We are also allowed to refer to "the ideal of the chair", thanks to the way we defined imitation. (Again, the relations chapter offers a much more detailed explanation of how relations may be defined.)
So far the effect is not very deep, but we could take the auto-description a great deal further: providing a larger and more interesting set of variations; or writing a complicated set of rules such that the player only notices height variations when carrying a ruler; or switching between several player-characters, each of whom notices a different subset of characteristics. But these refinements would require more input from later chapters. |
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Suppose we have an extremely detailed world model in which every object is characterized by many features -- in this example, material and height, though one could add more. Suppose further that we would like to generate descriptions of these things automatically for the most part, drawing the player's attention only to those aspects of the object that are particularly interesting.
So far, we have generally dealt with cases where the property of a thing can be a number (such as 3), a value (such as brightness), or a unit (like height, here). It is also possible for a thing to have a property which names another thing, as in "The mother of the baby trout is the large trout" -- where "mother" is a property, and its value, in the case of the baby trout, is large trout. We would define such a property with a line such as "A fish has a thing called the mother." In practice, though, this is a bit confusing as syntax; moreover, Inform has a much more powerful construct for talking about the ways in which one object relates to another object. A full discussion of this will have to wait for the chapter on Relations. For now, it is enough to say that we can do this:
This will allow us to declare that some objects imitate other objects, like so:
Now each of these types has one ideal representative which has the fundamental attributes of its kind: the ordinary chair is the most chairlike chair imaginable, the ordinary table is the epitome of tableness, and so on. We are also allowed to refer to "the ideal of the chair", thanks to the way we defined imitation. (Again, the relations chapter offers a much more detailed explanation of how relations may be defined.)
So far the effect is not very deep, but we could take the auto-description a great deal further: providing a larger and more interesting set of variations; or writing a complicated set of rules such that the player only notices height variations when carrying a ruler; or switching between several player-characters, each of whom notices a different subset of characteristics. But these refinements would require more input from later chapters.
Suppose we have an extremely detailed world model in which every object is characterized by many features -- in this example, material and height, though one could add more. Suppose further that we would like to generate descriptions of these things automatically for the most part, drawing the player's attention only to those aspects of the object that are particularly interesting.
So far, we have generally dealt with cases where the property of a thing can be a number (such as 3), a value (such as brightness), or a unit (like height, here). It is also possible for a thing to have a property which names another thing, as in "The mother of the baby trout is the large trout" -- where "mother" is a property, and its value, in the case of the baby trout, is large trout. We would define such a property with a line such as "A fish has a thing called the mother." In practice, though, this is a bit confusing as syntax; moreover, Inform has a much more powerful construct for talking about the ways in which one object relates to another object. A full discussion of this will have to wait for the chapter on Relations. For now, it is enough to say that we can do this:
This will allow us to declare that some objects imitate other objects, like so:
Now each of these types has one ideal representative which has the fundamental attributes of its kind: the ordinary chair is the most chairlike chair imaginable, the ordinary table is the epitome of tableness, and so on. We are also allowed to refer to "the ideal of the chair", thanks to the way we defined imitation. (Again, the relations chapter offers a much more detailed explanation of how relations may be defined.)
So far the effect is not very deep, but we could take the auto-description a great deal further: providing a larger and more interesting set of variations; or writing a complicated set of rules such that the player only notices height variations when carrying a ruler; or switching between several player-characters, each of whom notices a different subset of characteristics. But these refinements would require more input from later chapters. |
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