Section 1. Introduction ======================= 1.1 Prerequisite concepts ------------------------- In order to fully understand the add_command tutorial, you should have a basic understanding of the following concepts: ~ data types: string, int, object, mixed ~ arrays: referencing members of, adding to ~ variables: types of, local, global ~ objects ~ functions: defining, parameters of, passing arguments to, calling Specific sections of the tutorial assume prior understanding of these topics as well: function pointers: discussed in Sections 2.5 and 4.7 (see note) add_item() in rooms: discussed in Sections 4.6 and 5.? effects and shadows: discussed in Section 5.? Note: Function pointers are explained to a limited degree in sections 2.4 and 4.7. Understanding these will make those sections easier to grasp but is not required. 1.2 New terms and concepts The tutorial refers continually to "the parser". The parser itself is a collection of files that handle user input, ie: reading what a player types, taking it apart into pieces (parsing it), deciding what to do with it, and then carrying out those actions. For example, when you type "say bing!" it is the parser that takes your input, determines that 'say' is a command you know, and then initiates the process that makes you actually say "bing!" and tell others that you've done so. The parser does this (roughly) by looking first to see if the first thing you type (e.g. "say" or "'" for the say command) is a command you know. If it is, it consults the list of patterns it knows are associated with that command and compares all the rest of your input to these patterns. Add_command() allows a creator to tell the parser that a player or npc knows a new command and also tell it the pattern(s) it should use for comparison. The patterns themselves can be thought of as a kind of template or, better yet, as an exercise in filling in blanks. Take, for example, the command get. One of the syntaxes for get is "get <object>". That < > is like a blank waiting for the player (or npc) to fill it in. The label 'object' inside the < > tells the player and the parser both what the blank should be filled with. When a player types "get sword", the parser reads his input, decides the first word "get" is a command that the player knows, and then tries to match "sword" to the rest of the syntax, i.e. "<object>". If there actually is an object named "sword" in the player's environment, the parser is satisfied and the command "get" proceeds. If there is no such object in the player's environment, the parser decides that the <object> blank hasn't been filled in properly and tells the player to check the syntax for the command again. When adding a command to a player, it's your job to decide just what the pattern(s) associated with it should be. Section 3: Format Patterns is devoted to helping you do that. Until you get to that stage, have faith that the things you see in < > will make sense eventually.
