Today I've added alias() and unalias() methods to the
props.Node class:
var foo = props.globals.getNode("/foo", 1);
foo.alias("/sim/aircraft");
foo is now an alias to /sim/aircraft. It will have the
same node type (STRING) and return the same value as
/sim/aircraft. alias() does also accept a props.Node
as argument.
foo.unalias();
... removes the alias link, after which node "foo" will
be a regular node of type NONE, with no data relation to
/sim/aircraft or any other node. You can make an alias
to a tied node.
alias()/unalias() exist since a long time in C++ space,
but were not available on the Nasal side, because there
was no need in the beginning. But now with MP aliases
can be quite useful:
Assume you want to transmit your aircraft's door position
over MP. There are no pre-defined door MP properties, so
you have to use a generic node. You define something like
this in your *-set.xml file:
<sim>
<multiplay>
<generic>
<float n="0" alias="/sim/model/doors/door[0]/position-norm"/>
</generic>
</multiplay>
</sim>
But how does one get the generic values back to the remote
aircraft's door property? So far one had to create a loop
in the model animation XML file's <nasal><load> block, which
reads the generic value and copies it to the door property.
Now one can make an alias instead:
<load>
var self = cmdarg();
var door = self.getNode("sim/model/doors/door/position-norm", 1);
var generic = self.getNode("sim/multiplay/generic/float", 1);
door.alias(generic);
</load>
<unload>
door.unalias();
</unload>
The aliases do the "copying" (actually: redirecting) automatically
and are much more efficient.
m.
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