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Postings from October 2016
On Mon Oct 31 04:02:09 2016, haukex@zero-g.net wrote: > Hi, > > On 31.10.2016 06:39, Father Chrysostomos via RT wrote: > > On Sun Oct 30 17:51:24 2016, tonyc wrote: > >> > >> +It is possible to manually set C<@ISA>, but it is recommended to use > >> +L<parent> to declare parent classes. > >> > >> Is it recommended? > > > > By some and not by others. > > I copied that wording from perlobj: "It is possible to manually set > @ISA, and you may see this in older Perl code. Much older code also uses > the base pragma. For new code, we recommend that you use the parent > pragma to declare your parents. This pragma will take care of setting > @ISA. It will also load the parent classes and make sure that the > package doesn't inherit from itself." > > But that could certainly be toned down, see updated text below. > > >> This pragma will take care of setting > >> +C<@ISA> and will also load the parent classes and make sure that the > >> +package doesn't inherit from itself. > >> > >> Setting @ISA directly also checks for recursive inheritence: > >> > >> $ ./perl -e 'package Foo; our @ISA = "Bar"; package Bar; our @ISA = > >> "Foo";' > >> Recursive inheritance detected in package 'Bar' at -e line 1. > > Having never set @ISA manually (at least as far back as I can > remember...) I did not know that, thanks! > > > I think it would be better for perlvar to begin by explaining what > > the variable does and what it is for, and *then* also mention that > > parent.pm *can* be used to set it. > > The patch begins with an explanation of the variable's purpose which I > again mostly copied & adapted from perlobj. It doesn't discuss MRO but > links to perlobj. I'll gladly take any suggestions there. > > Updated suggestion: > > ---8<--- > Each package contains a special array called C<@ISA> which contains a > list of that class's parent classes, if any. This array is simply a list > of scalars, each of which is a string that corresponds to a package > name. The array is examined when Perl does method resolution, which is > covered in L<perlobj>. > > It is possible to manually set C<@ISA>, or you can use L<parent> to load > and declare parent classes. Alternatively there is the L<base> pragma, > but that is discouraged unless you're also using the L<fields> pragma. > --->8--- > > If that's better I'd be happy to produce a new patch. I do think that is better. Thank you. -- Father Chrysostomos --- via perlbug: queue: perl5 status: open https://rt.perl.org/Ticket/Display.html?id=129967Thread Previous | Thread Next