(Ovid) Re: Autoload'ed class method calls

The easy way to explain this is to consider a typical constructor.

sub new {
    my $class = shift;
    my $data = {};
    bless $data, $class;
    return $data;
}
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Now, why is the first argument to the constructor called $class instead of $self? Because when the constructor is called properly, the first argument to it is the name of the class (as a string), not an object. This is because you haven't created the object yet!

$package = WM::Install::Table::ArchiveTbl->get_pkgname();
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The previous line of code cannot work with the current structure of your AUTOLOAD because the first argument will be the classname and not a hashref. Either call the method from an instance of the class or recode your AUTOLOAD.

Cheers,
Ovid

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Re: (Ovid) Re: Autoload'ed class method calls by rinceWind (Monsignor) on Apr 05, 2002 at 18:36 UTC
Ovid, not sure that hackdaddy has got it wrong. His code is the AUTOLOAD sub, not the constructor. I presume he will be supplying his own `new` sub so that AUTOLOAD will not be called on construction. More importantly, he needs to declare $AUTOLOAD in package namespace, with `use vars qw($AUTOLOAD);` [download] or `our $AUTOLOAD;` [download] The rest seems to go through `use strict 'refs'`OK. Update: Ovid I am humbled! It's interesting how staring at a piece of code can lead you to wrong conclusions (in my case exacerbated by lack of sleep and coffee). It also shows what a snarfy beast AUTOLOAD can be. I've written pseudo-methods in AUTOLOAD myself, but usually solved problems like hackdaddy's by stepping through with the debugger.	[reply] [d/l] [select]
(Ovid) Re(3): Autoload'ed class method calls by Ovid (Cardinal) on Apr 05, 2002 at 18:46 UTC
Read through his code and error message again. hackdaddy already has `$AUTOLOAD` declared properly, otherwise the first method call would fail, but according to hackdaddy, it's successful. However, read through the text of the actual error message. `Can't use string ("WM::Install::Table::ArchiveTbl") as a HASH ref whil +e "strict refs" in use at /u08/pkg/wms/wmcmtools/modules/WM/Install/Table/ArchiveTbl.pm line +192.` [download] Now look at first few lines of the autoload. `sub AUTOLOAD { my ($self, $newval) = @_; $AUTOLOAD =~ /.::get(_\w+)/ and $self->_accessible($1) and return $self->{$1};` [download] As you can see, the return statement (`return $self->{$1}`) is attempting to use `$self` as a hashref. Since the error messsage shows that the programmers is trying to use the package name as a hashref, we clearly have the package name and not the object* being passed as the first argument to `AUTOLOAD`. I was using a generic constructor to illustrate how the first argument could be a package name instead of an object, as expected. Cheers, Ovid PS: I'm also a Terry Pratchett fan (I'm assuming that's what your nick refers to). Join the Perlmonks Setiathome Group or just click on the the link and check out our stats.	[reply] [d/l] [select]