Basic Hyperlinks

version 3 by Emily Short

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    Basic Hyperlinks allows us to annotate pieces of output text as hyperlinks, assigning a number to each one. For instance, we might have

        Mossy Bank is a room. "The shore here is made up of round rocks, very heavily grown over with a slippery grey-green moss. To the [set link 1]north[end link] is a small shack."

    This tells Inform that we want to make 'north' here a hyperlink, and that we are assigning this link the number 1. We should not attempt to nest hyperlinks, as the results are likely to be messy.

    We will also need to cause a result when the link is clicked; this is where the clicking hyperlink rulebook comes in. We might write, for instance,

        A clicking hyperlink rule when the current link number is 1:
            ...

    ...and this would provide a reaction when that link is clicked. If we have a very large number of hyperlinks in our game, we might want to set up the links in a different way -- for instance, by building a table relating numbers to outcomes. This could also be done using a clicking hyperlink rule. In fact, this is so often what we want to do that our default clicking hyperlink rule says

        A clicking hyperlink rule (this is the default command replacement by hyperlinks rule):
            repeat through the Table of Hyperlink Glulx Replacement Commands
            begin;
                if the current link number is linknum entry
                begin;
                    change the glulx replacement command to replacement entry;
                    rule succeeds;
                end if;
            end repeat;
            now glulx replacement command is "".

    which expects us to provide a table of command outcomes such as

        Table of Hyperlink Glulx Replacement Commands (continued)
      linknum  replacement  
      1  "north"  
      2  "take lantern"  

    and so on. The "glulx replacement command" is some text that varies -- actually a feature of the Glulx Entry Points extension on which this one depends -- and it allows us to write in something as though the player had typed it at the command prompt. Because the link is only pasting in a command on behalf of the player, we could then use link 1 over and over throughout the game any time we wanted a hyperlink that led north: the effect will always be to paste >north at the command prompt.

    But if we would prefer to have hyperlinks do other things, we may remove the default rule like this:

        The default command replacement by hyperlinks rule is not listed in any rulebook.

    ...and then replace it with clicking hyperlinks rules of our own.