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MultipleInheritance.pm
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MultipleInheritance.pm
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role Perl6::Metamodel::MultipleInheritance {
# Array of parents.
has @!parents;
# Are any of the parents hidden?
has @!hides;
# Is this class hidden?
has $!hidden;
# Classes to exclude from the parents list in introspection by default.
my @excluded;
method exclude_parent($parent) {
@excluded.push($parent);
}
# Adds a parent.
method add_parent($obj, $parent, :$hides) {
if self.is_composed($obj) {
nqp::die("Parents cannot be added to a class after it has been composed");
}
if $parent =:= $obj {
nqp::die("Class " ~ self.name($obj) ~ " cannot inherit from itself");
}
for @!parents {
if $_ =:= $parent {
nqp::die("Package '" ~ self.name($obj) ~
"' already has parent '" ~
$parent.HOW.name($parent) ~ "'");
}
}
if $hides {
@!hides[+@!hides] := $parent;
}
@!parents[+@!parents] := $parent;
}
# Introspects the parents.
method parents($obj, :$local, :$tree, :$excl, :$all) {
if $local {
@!parents
}
elsif $tree {
my @result;
for @!parents {
my @pt := [$_];
@pt.push($_.HOW.parents($_, :tree(1)));
@result.push(pir::perl6ize_type__PP(@pt).Array.item);
}
return pir::perl6ize_type__PP(@result);
}
else {
# All parents is MRO minus the first thing (which is us).
my @mro := self.mro($obj);
my @parents;
my $i := 1;
while $i < +@mro {
my $exclude := 0;
unless $all {
for @excluded {
$exclude := 1 if @mro[$i] =:= $_;
}
}
@parents.push(@mro[$i]) unless $exclude;
$i := $i + 1;
}
@parents
}
}
method hides($obj) {
@!hides
}
method hidden($obj) {
$!hidden ?? 1 !! 0
}
method set_hidden($obj) {
$!hidden := 1;
}
}