Re: Glib::Object::Subclass and Exporter

[Kevin Ryde <user42 zip com au>]

Domovoy <domovoy errlock org> writes:
> So, i finally took a look at Glib::Object::Subclass.pm, and saw that it
> was doing its job by defining an import sub.

And putting itself at the start of the caller's @ISA ...

>       use Glib::Object::Subclass
>           Gtk2::ScrolledWindow::;
>  
>       BEGIN {
>           require Exporter;
>           our @ISA = qw(Exporter);

This is a store to @ISA, replacing the bits Glib::Object::Subclass put
there, hence those bits not working.

I get some joy from changing it to

    unshift @ISA, qw(Exporter);

so that Exporter is at the start of @ISA and everything from
Glib::Object::Subclass follows.

Perhaps the way Glib::Object::Subclass pushes itself onto @ISA to get a
perlish new() could be better done by pushing a separate class which had
only new().  Then any import() in the caller, or the caller's
inheritance, wouldn't be affected in the way you struck.

In practice I suspect Exporter is not much used with oopery.  Constants
can be offered as class methods

    $c = Foo::Bar->SOME_CONST;

which has the advantage of working from instances too

    $c = $foo->SOME_CONST;

Such a call is a very tiny bit slower (and won't constant-fold), but has
the advantage that further subclasses can override.



>           bless($self, $class);

This ought to be unnecessary.  If it is necessary then you're either
doing something wrong, or something very advanced :-).




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