Grammar

Your new game will almost always require the creation of new verbs that are specific to your world. These new verbs need to be defined with a grammar definition. This is very easy in Hugo.

The syntax for grammar definition is

[x]verb "<verb1>" [, "<verb2", "<verb3>", ...]
* <syntax specification 1>           <VerbRoutine1>
* <syntax specification 2>           <VerbRoutine2>
...

Where “<verbX>” is the verb you’re defining. Multiple verbs can be defined for one grammar rule. These are synonyms for each other (so you can have ‘attack’, ‘hit’, ‘punch’ all do the same thing.)

Here are a couple of examples from the verblib.g grammar file included in the standard hugo library.

verb "get"
    *                   DoVague
    * "up"/"out"/"off"          DoExit
    * "outof"/"offof"/"off" object      DoExit
    * "in"/"on" object          DoEnter
    * multinotheld "from"/"off" parent  DoGet
    * multinotheld "offof"/"outof" parent   DoGet
    * multinotheld              DoGet

Line by line:

This line is telling the compiler that we are defining a new, normal verb called get
The * is a place holder for the verb(s) defined in line one, this line is saying that we need to call the routine DoVague if the line contains only get
This line we are defining what to do when the player types get up (or get out or get off)
This line shows what to do when the player types get out of object. The hugo parser will concatenate out of, or off of to outof or offof for easier parsing.
What to do if the player types get in or get on some object. (Call the DoEnter routine)
multinotheld means multiple things that are not held by the player. (ie. get apple, peach and pie from the table)
What to do when the player types get <objects> off of object.
What to do if the player just types something like get apple and banana

xverb "save"
    *       DoSave
    * "game"    DoSave

This defines what to do when the player types either save or save game. This is an xverb. An xverb is a verb that does not call the Main routine when it successfully completes it action. This means that the turn counter will not be incremented. xverbs are generally used for ‘out of world’ actions, actions that are for non-action, housekeeping-type verbs (such as saving, quitting and restarting)

verb some_object?

The Grammar & Parsing section of the Hugo Book has a section on directing a verb definition to an object’s noun property. If it worked as described, one could have a somewhat dynamic verb which changed as the game progressed. It doesn’t currently work, though, so in the meantime (while it is looked into), don’t waste your time with it!

verb some_object?

See also: