Channel 2
Television with more advanced parsing
Example 316
★★★Our previous implementation of televisions ("Channel 1") doesn't allow the player to type things like
TUNE FIFTIES TELEVISION TO CHANNEL 4
nor does it deal with player input like
TUNE TO CHANNEL 4 ON FIFTIES TELEVISION
or
TUNE TO CHANNEL 4
where no television is specified. When we are designing commands which involve two elements (here, a television and a channel number), it's usually a good idea to allow the player to specify those elements in either order, as we saw demonstrated briefly in "New commands for old grammar".
We might, therefore, want to add a few refinements: first by defining a "[channel]" token that will accept input of the forms "[number]" and "channel [number]", and second by creating some additional "Understand" lines that will accept variant versions of the player's input.
"Channel 2"
Section 1 - Televisions in General
A television is a kind of device.
A television has a number called the channel. Understand the channel property as referring to a television. Understand "channel" as a television.
Changing the channel of it to is an action applying to one thing and one number.
Understand "tune [television] to [channel]" or "change channel of [television] to [channel]" as changing the channel of it to.
Understand "tune [something] to [channel]" or "change channel of [something] to [channel]" as changing the channel of it to.
Understand "tune to [channel] on [television]" or "change to [channel] on [television]" as changing the channel of it to (with nouns reversed).
Understand "tune to [channel] on [something]" or "change to [channel] on [something]" as changing the channel of it to (with nouns reversed).
Understand "[number]" or "channel [number]" as "[channel]".
Check changing the channel of something to:
if the noun is not a television, say "[The noun] cannot be tuned to a channel." instead.
Carry out changing the channel of something to:
now the channel of the noun is the number understood.
Report changing the channel of something to:
say "You tune [the noun] to channel [number understood]."
Instead of examining a television:
if the noun is switched off, say "[The noun] is currently turned off." instead;
let the chosen channel be the channel of the noun;
if the chosen channel is a current channel listed in the Table of Television Channels:
choose row with current channel of the chosen channel in the Table of Television Channels;
say "[output entry][paragraph break]";
otherwise:
say "Snow fills the screen of [the noun]."
Table of Television Channels
| current channel | output |
| 0 | "The screen of [the noun] is completely black." |
Section 2 - The Scenario
The Office is a room.
The widescreen TV is a television in the Office. The fifties TV is a television in the Office.
And we add the scenario-specific content to our Table of Television Channels; in the case of channel 13, we provide for a changing sequence of events using text variations.
Table of Television Channels (continued)
| current channel | output |
| 4 | "A gloomy female news anchor describes the latest car bomb in Baghdad: 104 dead today, and no sign of change." |
| 5 | "A couple of contestants in spangled scarlet outfits are performing an energetic paso doble." |
| 13 | "[one of]On-screen, Ichiro is up to bat with one man on second and no outs.[or]Ichiro has singled to first and the other man is on third.[or]The next batter is in the middle of flying out.[or]Everything looks rosy until the men in black pull off a double-play and retire the side.[or]The channel has cut to a commercial.[stopping]" |
Test me with "test one / test two".
Test one with "change channel of fifties tv to 4 / x channel 4 / switch on fifties / x channel 4 / switch on widescreen / tune fifties tv to channel 5 / x channel 5 / x fifties tv / x channel 4".
Test two with "tune to channel 13 / widescreen / tune channel 13 to channel 5 / tune channel 5 to channel 3 / widescreen / x channel 3".
Test me with "test one / test two".
Office
You can see a widescreen TV and a fifties TV here.
>(Testing.)
>[1] test one
(Testing.)
>[2] change channel of fifties tv to 4
You tune the fifties TV to channel 4.
>[3] x channel 4
The fifties TV is currently turned off.
>[4] switch on fifties
You switch the fifties TV on.
>[5] x channel 4
A gloomy female news anchor describes the latest car bomb in Baghdad: 104 dead today, and no sign of change.
>[6] switch on widescreen
You switch the widescreen TV on.
>[7] tune fifties tv to channel 5
You tune the fifties TV to channel 5.
>[8] x channel 5
A couple of contestants in spangled scarlet outfits are performing an energetic paso doble.
>[9] x fifties tv
A couple of contestants in spangled scarlet outfits are performing an energetic paso doble.
>[10] x channel 4
You can't see any such thing.
>[11] test two
(Testing.)
>[12] tune to channel 13
What do you want to tune to that on?
>[13] widescreen
You tune the widescreen TV to channel 13.
>[14] tune channel 13 to channel 5
You tune the widescreen TV to channel 5.
>[15] tune channel 5 to channel 3
Which do you mean, the widescreen TV or the fifties TV?
>[16] widescreen
You tune the widescreen TV to channel 3.
>[17] x channel 3
Snow fills the screen of the widescreen TV.
You can see a widescreen TV and a fifties TV here.
>(Testing.)
>[1] test one
(Testing.)
>[2] change channel of fifties tv to 4
You tune the fifties TV to channel 4.
>[3] x channel 4
The fifties TV is currently turned off.
>[4] switch on fifties
You switch the fifties TV on.
>[5] x channel 4
A gloomy female news anchor describes the latest car bomb in Baghdad: 104 dead today, and no sign of change.
>[6] switch on widescreen
You switch the widescreen TV on.
>[7] tune fifties tv to channel 5
You tune the fifties TV to channel 5.
>[8] x channel 5
A couple of contestants in spangled scarlet outfits are performing an energetic paso doble.
>[9] x fifties tv
A couple of contestants in spangled scarlet outfits are performing an energetic paso doble.
>[10] x channel 4
You can't see any such thing.
>[11] test two
(Testing.)
>[12] tune to channel 13
What do you want to tune to that on?
>[13] widescreen
You tune the widescreen TV to channel 13.
>[14] tune channel 13 to channel 5
You tune the widescreen TV to channel 5.
>[15] tune channel 5 to channel 3
Which do you mean, the widescreen TV or the fifties TV?
>[16] widescreen
You tune the widescreen TV to channel 3.
>[17] x channel 3
Snow fills the screen of the widescreen TV.