Allow variables in links to passages

[factorypreset]

Suggested by Strangelander (via email):

The only ability I think Twine absolutely needs to add is the ability to set a variable to a passage title and then go to the passage using the variable, something like:

<<set $nextPlace = "Basement stairs">>
[[<<$nextPlace>>]]
or
[[Go down|<<$nextPlace>>]]
and
<<if $monsterDead>><<display $nextPlace>><<endif>>

[HarmlessTrouble]

Philip Requested i take a look at this issue.

<<display $variable>> is easy enough

(and a solution has been recently offered from CodeDuck https://groups.google.com/forum/?fromgroups#!searchin/tweecode/%3C%3Cdisplay/tweecode/9OggpvgERWA/yjDdVNHuCDQJ)

while this is good to have, this isn't a true dynamic link.

Wikifier.formatters seems to match [[]] and <<>> in one pass. so to get something like say [[<<print $Passage>> |<<print $Passage>>]] to work all we would need to do pass the content of the internal link through the "macro"formatter in a line just before the Wikifier.createInternalLink is used inside the "prettyLink " formatter.

[HarmlessTrouble]

Here's a macro equivalent for generating dynamic links,

< < dynamiclink [passagename] [linktext]> >

macros.dynamiclink = {handler: function(a,b,c){ var d; try{d = eval(Wikifier.parse(c[0]));}catch(e){d=c[0];} if (c[1]){ var f; try{f = eval(Wikifier.parse(c[1]));} catch(e){f=c[1];} }else{e=c[0]} el=document.createElement("a"); el.className="internalLink"; el.href="javascript: void(0)"; el.onclick=function(){state.display(d,el)} el.innerHTML=d; if (f){el.innerHTML=f;} a.appendChild(el) }};

INext, 'll try to use this technique directly inside the "prettyLink" formatter.

[HarmlessTrouble]

using print macro technique to render dynamic links is imo sufficient to satisfy this functionality.

Any objections to closing this feature request?