I'm not sure what choroba said in response to this question, and these comments are in the context of general Perl OO practice and not Moo, but ...
... "Does $self->new make sense?" ...
I sometimes see constructor code that looks something like
sub new {
my $class_or_objref = shift;
my $ref_class = ref $class_or_objref; # true if an object referen
+ce
my $object_reference;
if ($ref_class) {
# build object reference from existing object attributes
# and supplied @_ arguments.
}
else {
# build object reference for class from supplied @_ arguments.
}
return $object_reference;
}
To me, this factors naturally as
sub new {
my $classname_or_objref = shift;
return ref $classname_or_objref ? $classname_or_objref->new_clone
+ (@_)
: $classname_or_objref->new_pristi
+ne(@_)
;
}
(Update: From this point on, @_ | no, changed my mind, will use ... (yada) for this notation represents a general argument LIST, possibly empty.)
So every class/package may potentially need both a
$object_reference->new_clone(...)
method that builds and returns a new object reference based on the attributes of an existing object and any additional arguments supplied, and a traditional
ClassName->new_pristine(...)
method that builds and returns a new object reference based solely on a class name bareword/string and any arguments. It's immediately obvious that
ClassName->new_pristine(...)
looks a lot like the very familiar
ClassName->new(...)
usage, and
$object_reference->new_clone(...)
can very intuitively be represented simply as
$object_reference->clone(...)
IMHO, there is no value added by trying to combine object clone creation with "classic" object construction. The calls
my $obj = ClassName->new(...);
and
my $obj = $existing_object_reference->clone(...);
should do exactly what you expect them to do and no more. A ClassName->new constructor definition can often be very short, sweet and easy to understand; don't clutter it up with unnecessary stuff. If no clone() constructor is needed for a class (and it usually isn't), don't define one. So, in answer to the question, $self->new can make sense, but usually doesn't, and certainly not with that method name.
... does Perl have something similar to new XYZ; which will search for the nearest new() all the way up the inheritance tree of XYZ?
IIRC, any ClassName->method() or $objref->method() call will search for method() first in the specified class (either explicitly named or embedded in the object reference) and then all the way up the @ISA tree of the specified class under the control of the mro (available with Perl version 5.10+) currently selected, and then into the UNIVERSAL class. (And, of course, new has the same status as any other method name. It is used as a constructor name by convention; any other — well documented! — name could be used.)
Give a man a fish: <%-{-{-{-<
|