Perl TM Tutorial: As Low as it Gets (Part III)
(Followup to part II)
Looking up assertions with match_forall works, but is cumbersome if you just want to find instances, types, subtypes or supertypes of a given toplet.
To experiment with this here, we need some topic map with just a few types, subtypes and some instances for these. Instead of creating them programmatically, we write the map in one of the convenient text notations and let a parser do the job.
For the notation we choose (the old and trusty) AsTMa:
my $tm = new TM::Materialized::AsTMa (inline => '
The map features sacklpicka as an instance of cat and rho as an instance of human.
After loading a package supporting the notation, we instantiate our map object $tm. As we are too lazy to store the AsTMa text in a file, we use the option to specify AsTMa code inline. Still, we have to tell the map to read and deserialize the content now:
More about persistent maps later.
As you would expect, sacklpicka will be listed as instance of cat:
warn Dumper [ $tm->instances ($tm->tids ('cat')) ];
Since mammal does not have any direct instances, the following list will be empty:
To eventually reach also those instances which are instances of any of mammal's subtype(s), you will have to use the transitive version.
In a similar vein the TM package offers functions to learn about
- the subclasses, direct and indirect
- any superclasses, direct and indirect, and
- any types, also direct and indirect ones.
Since such taxonometric functions are pretty important, there is also a set of functions just for boolean tests:
if $tm->is_a ($tm->tids ('sacklpicka', 'cat'));
warn "Not sure about that"
unless $tm->is_subclass ($tm->tids ('cat', 'mammal'));
Note how the tids function can accept lists.
Finally, there are also variants to be used as filters for a certain class:
Sadly, at this stage the other filters are_types, are_supertypes and are_subtypes are not yet implemented.
Send more chocolate if you need them. Better than sending patches ...
Work supported by the Austrian Research Centers.